Volkswagen
Fixes.
Repacking Front
Wheel Bearings
This procedure is based on the
Haynes Manual, with notes from John Muir and Rob Boardman.
NOTE: The front wheel bearings should be serviced every 30,000 miles and/or when
the brake linings are changed. Additionally, the bearings should be checked
whenever the front of the vehicle is raised for any reason.
1. Raise the vehicle and support it securely on jackstands. Spin each wheel and
check for noise, rolling resistance and freeplay. The wheels should turn freely
without binding.
2. Grasp the top of each tire with one hand and the bottom with thej other. Move
the wheel in-and-out on the spindle. If there's any noticeable movement, the
bearings should be checked and then repacked with greases or replaced if
necessary.
3. Remove the wheel.
4. On the driver's side, remove the clip from the end of the speedometer cable.
On both sides, pry the dust cap off the hub.
5. Loosen the spindle nut lockbolt with a 6mm Allen wrench.
6. Remove the spindle nut and washer from the end of the spindle.
NOTE: The left side spindle has left hand threads.
7. Pull the hub assembly out slightly, then push it back into its original
position. This should force the outer bearing off the spindle enough so it can
be removed.
8. Pull the hub assembly off the spindle.
9. Use a screwdriver to pry the seal out of the rear of the hub. As this is
done, note how the seal is installed.
10. Remove the inner wheel bearing from the hub.
11. Use solvent to remove all traces of the old grease from the bearings, hub
and spindle. A small brush may prove helpful; however, make sure no bristles
from the brush embed themselves inside the bearing rollers. Allow the parts to
air dry.
12. Carefully inspect the
bearings for cracks, heat discoloration, worn rollers, etc. Check both the inner
and outer bearing races inside the hub for wear and damage. If the bearing races
are defective, the hubs should be taken to a machine shop with the facilities to
remove the old races and press new ones in. Note that the bearings and races
come as matched sets and old bearings should never be installed on new races.
13. It is possible to install the new outer race yourself. Clean the wheel hub
thoroughly. Hold the whole bearing up to the hub to make sure you know how it
goes, with the heavy part in, then get the outer race started in the hole evenly
all around. Use two hammers, one on the race and one to tap it with. Tap this
race into the hub until it is inside the hub, then tap it in with a dull chisel
until the race is seated on the shoulder of the hub. You can tell by the solid
sound when it's seated. Now proceed to packing the bearings.
14. Repack both the inner and outer bearings with high-temperature front wheel
bearing grease.
NOTE: Make sure the bearings are absolutely clean and dry. If they still have
solvent on them (if you're replacing them, not putting new ones in), you cannot
pack them until they have dried completely so put them in the sun and wait.
15. With the bearing in the palm of your hand, work the grease completely into
the rollers, forcing it between the rollers, cone and cage from the back side.
16. Apply a thin coat of grease to the spindle at the outer bearing seat, inner
bearing seat, shoulder and seal seat.
17. Put a small quantity of grease inboard of each bearing race inside the hub.
Using your finger, form a dam at these points to provide extra grease
availability and to keep thinned grease from flowing out of the bearing.
John Muir says to pack the
hub full of grease. It will take about 50 grams of wheel bearing grease, a small
handful. Start jambing the wheel bearing grease into the outboard end of the
drum hub. Covering the inboard hole in the hub with your hand, fill the whole
hub completely. Push the grease in really well, think of the 30,000 miles and
smile.
Note from Rob Boardman: The bearings are not sealed themselves, so the hub needs
to be packed with grease. This supplies a very large quantity of grease to the
bearings, and so they last a long time. If the grease is renewed about every
30,000 miles (the grease seal too) the bearings will last forever.
If this process is done right, you'll probably find that the NEXT time you do it
- there will be a small ridge of grease around the inside of the end (bearing)
cap - close to the bearing. This means that the hub was nice and full, as when
it got warm and expanded, a little was pushed out past the outer bearing and the
spinning wheel stuck it to the inside of the bearing cap.
18. Place the grease-packed inner bearing into the rear of the hub and put a
little more grease outboard of the bearing.
19. Place a new seal over the inner bearing and tap the seal evenly into place
with a hammer and block of wood until it's flush with the hub.
The grease seal is rubber
coated, and has a spiral spring around a groove in the seal. This spring keeps
the inner sealing lip in contact with the axle as the wheel and seal rotate.
This spring must face the inside of the bearing, so you only see the back of the
seal when you install it. place the drum on a clean flat surface - smear a thin
coat of grease on the seal where is will slide into the drum, place it on the
drum and place a piece of smooth flat wood over the back of the seal. Now tap
the wood with a mallet or hammer, gently working around the perimeter of the
seal so it goes in a little at a time. It doesn't take a lot of force, but must
be done evenly around the perimeter of the seal so it doesn't end up distorted.
20. Carefully place the hub assembly onto the spindle.
Note from John Muir: Wipe your greasy hands clean again, grab the hub and push
it onto the axle. Help is nice at this point as you are trying to put the wheel
on the axle while keeping grease in the hub with your third and fourth hands. As
soon as the axle appear out the hub, pick up the outboard bearing and push it
on, as it helps to hold the grease in. Don't be so enthusiastic about shoving
grease back that you push it out the back hole. Just use all that it will hold.
Note from Rob Boardman: Any grease which get pushed out as the axle comes
through is easy to push back in by running a finger round and round the axle.
21. Push the grease-packed outer bearing into position.
22. When the axle is out as far as it will come, tap the outboard bearing into
its race and the hammer and dull chisel. Lift the wheel straight up with your
foot so you can tap the bearing in. Clean up around the place with a little rag
or rags, then go to the next step and adjust the bearings.
Note from Rob: The race has
been fitted previously of course, so this just means inserting the bearing cage
over the axle.
23. Install the washer and spindle nut. Tighten the nut only until all freeplay
is gone.
Note from Rob: Nice and snug - as I've mentioned before. You should feel the
drum start to bind. Keep turning the wheel/drum as you do this to help the
bearing seat all the way in.)
24. Spin the hub in a forward direction to seat the bearings and remove any
grease or burrs which could cause excessive bearing play later.
25. Check to see that the tightness of the spindle nut is still the same.
26. Tighten the nut by hand until all looseness and freeplay are gone. Now
tighten the nut with a wrench approximately an addition 1/4 turn to create a
very slight preload, than back it off about 1/8 turn. The acceptable amount of
endplay is 0.001 to 0.003 inch.</LI<< P>
Note from Rob: I haven't done it exactly this way - just tightened it up till it
started to bind, loosened it until the binding was free, then HAND (or a very
light hand on a wrench) tightened it until it was just touching against the
washer, then grab the upper and lower edges of the drum and push-pull to check
for any play (look closely at the grease around the small bearing/washer/nut to
see if it "bulges" as you push-pull). Re-do the tightening sequence if
necessary. If it's loose the wheel will wobble - even if you can't feel it - and
wear the bearings out, and if it's too tight, there will be insufficient grease
between each roller and the race, so the bearing will run hot.
27. Tighten the spindle nut lock bolt with an Allen wrench to hold the spindle
nut in place.
Note from John Muir: Put the washer on the axle, then the ... nut (left axle has
left-hand threads).
From Rob: Good point that one. Designed so that if the allen key is not tight
enough, the rolling wheel/drum will tend to do the nut up, rather than loosen
it.
28. Use the crescent wrench to run this nut up pretty tight (7 ft-lb) while you
hand turn the drum. This turning will take the slack out of the bearings. Now
loosen the nut with the crescent a little at a time until you can just move the
washer under the nut with the big screwdriver. Tighten it again, then loosen it
until you can just move the washer. When that washer first moves upon prying it,
this is the point that gives the wheen about .001" of end play.
29. Install the dust cap on the passenger's side, tapping it into place with a
rubber mallet.
30. On the driver's side, reach behind the spindle and push the speedometer
cable through the dust cap. Then install the dust cap and reinstall the clip to
hold the speedometer cable in place.
31. Make sure that the studs in the brake drum are tight and secured with
Loktite. Install the wheel on the studs in the hub and tighten the lug nuts.
32. Grasp the top and botom of the tire and check the bearings in the manner
described earlier.
33. Lower the vehicle.
Remove/Install
Instrument Cluster/Speedometer Cable
NOTE: For this procedure,
"front" will mean the side of the instrument cluster from which the driver views
the gauges; "back" will mean the side of the instrument cluster to which the
speedometer cable and the various wires are attached. This use of "front" and
"back" is opposite that normally used in discussing VWs, where "front" means the
front of the car and "back" means the back of the car.
Instrument Cluster Removal:
1. Detach the cable from the negative battery terminal.
2. Remove the instrument cluster by carefully prying it away from the dash with
your fingers (if you use a screwdriver, be very careful not to scratch the dash
or the bezel around the instrument cluster.
NOTE: The instrument cluster is just pressed into the dash and held in place by
a ribbed rubber boot that fits around it.
3. Disconnect the speedometer cable from the speedometer by unscrewing the
threaded fitting that attaches it to the back of the instrument cluster. This
fitting should only be finger tight.
4. If you need to take the instrument cluster completely out of the car draw and
diagram of the back side of the instrument cluster and clearly label all of the
wires (there are a total of twelve connection points). It is also a good idea to
note all of the wire colors on your diagram just to make sure.
Speedometer Cable Removal:
1. Firmly set the parking brake, block the rear wheels, raise the front of the
car and set it firmly on jack stands.
2. Remove the circlip which secures the
end of the cable to the wheel bearing dust cap.
3. Working from the back side of the wheel, pull the cable out of the steering
knuckle.
4. Pull the speedometer completely out through the hole in the dash.
NOTE: It will help to have an assistant under the car as you slowly pull the
cable out so he can note the routing. Getting the new cable back in can be
tricky.
Speedometer Cable Installation:
1. Pull the cable right out of it's sheath, wipe it clean with a rag, and rub
grease down it's length with your fingers. Reinsert the cable in the sheath.
NOTE: If you are just lubricating a cable that you plan to reuse, grease it
carefully, as you may find a 'sprung' wire or two, and wire punctures in the
skin HURT. This will also tell you if it needs replacing again :-) The cable
usually breaks near the wheel end, as this bit gets flexed in all directions and
the wheel bounces and steers.
2. It's a good idea to install a new rubber sleeve in the steering knuckle to
keep water out. If water gets into the knuckle, it can damage the bearings and
allow the cable to freeze--and stick--in the winter.
3. Working with one person in the car and one person under the car, route the
new cable from the hole in the dash through the hole in the firewall (there
should be a grommet in this hole) and on down to the back side of the steering
knuckle, following the same route that the old cable took.
NOTE: Route the cable to eliminate sharp
bends (no radius less than six inches). Make sure it isn't kinked or pulled too
tight anywhere in the turning radius of the front wheel. Be careful not to
unseat the grommet when threading the new cable through.
4. Insert the wheel-end of the cable into the steering knuckle (from the back
side). You will probably have to remove the dust cover to get the end of the
cable properly aligned in the square hole. Install a new circlip at the end of
the cable.
NOTE: It is actually the dust cap which turns the cable and thus drives the
speedometer and odometer. Make sure the end of the cable is seated securely in
the dust cap.
5. Screw the threaded fitting on the dashboard end of the speedometer to the
back of the instrument cluster.
Instrument Cluster Installation:
1. Carefully reattach all of the wires (12) to the back of the instrument
cluster, making doubly sure that each attaches at the correct point.
2. Orient the cluster properly and press it back into the hole in the dash.
Types of Ignition –
Introduction
-
We have now tracked the fuel/air mixture from the
carburetor, through the intake manifold, and into the cylinders by way of the
intake valve. In the cylinders the fuel/air mixture is ignited by the spark
plug, and the action within the engine begins. The ignition system is designed
to get spark to the cylinders to burn the fuel to make the power to turn the
engine, the transmission, and the differential and, finally, the wheels.
Look to a little left of the center of the engine and
find a brown or black round plastic thing with five heavy wires sticking out of
it. That's the distributor cap.
By the way, Front means the
Front of the car and in the United States the "driver's side" is the left
side. In England, Australia, etc. the "driver's side" is the right side.
Under the distributor cap is the distributor and
inside the distributor are the rotor, the points and sometimes the
condenser, but usually the condenser, which is a small cylinder, is
attached to the outside of the distributor. The function of the condenser is to
smooth and control the low voltage spark and keep the points from burning and
pitting too rapidly.
There may be a bright metal biscuit, about 3" in
diameter, on the side of the distributor with one or two metal or rubber hoses
leading out of it; this is the vacuum advance. If you don't have this
biscuit, your distributor is a centrifugal advance type.
When the ignition key is turned on, electrical current
goes from the battery to the ignition coil, usually mounted on fan
housing. Inside the coil are thousands of turns of wire, which increases the
voltage to something like ten thousand volts, which is now available at the
center large outlet from the coil and connects to the center large connection at
the distributor cap. It takes a lot of voltage to make a spark jump across the
spark plug gap, and this is the way we get it.
The coil also has two side connections where smaller
wires are either bolted or push-on connected. On one side is a thin wire that
goes from the coil to the distributor (usually green); on the other side are a
wire that brings juice from the ignition switch, a wire that goes to the
automatic choke, a wire to the carburetor cut-off jet, and a wire to the back-up
lights.
The function of the distributor is to time the
spark impulses to the spark plugs so that they fire at the proper time so as to
burn the compressed fuel/air mixture, drive the pistons, and provide power to
the car. The distributor shaft is driven round and round by a gear on the
crankshaft. As it goes round and round inside the distributor it opens and
closes a set of ignition points.
The distributor shaft inside the distributor is almost
square, and at each point of the square it opens the ignition points. In between
the high places the points close. When the points are closed, the twelve volt
current (or six volt in older VWs) from the key is built up to high voltage
(think of it as pressure) in the coil so that when the points open there is
plenty of voltage to make the spark jump from the rotor to the pin inside the
distributor cap and thus through the heavy wires to the spark plugs,
providing a hot spark to burn the compressed fuel/air mixture in the cylinders.
So when the points open there are two sparks that jump
in the distributor cap -- one 12-volt (or 6-volt) spark in the bottom between
the points, and one high-voltage spark in the distributor cap.
Back to the heavy wires coming out of the distributor
cap. These are the spark plug wires which carry high voltage current from
the distributor to the spark plugs, which are down on either side of the
engine. Two go to the right to cylinders 1 (front) and 2 (rear), and the other
two go to the right to cylinders 3 (front) and 4 (rear). On the spark plug end
of each heavy wire is a plastic spark plug connector which screws onto
the end of the wire.
NOTE: You must never pull on
the spark plug wire -- always pull on the plastic connector to get the connector
off of the spark plug -- they just push on.
Around the
plastic spark plug connector is a rubber seal which keeps air from coming out of
the shrouding (all that tin around the engine). These seals must always be in
good condition and pushed into place so as to seal the air in; otherwise cooling
air from the fan will leak out and the engine will get hot. If they are beat,
make a note to get new ones and put them on.
To summarize: The high-voltage current passes from the center of the coil
through the center of the distributor cap to the rotor. From there the current
jumps to the post in the cap and through the proper wire to the proper spark
plug to ignite the compressed fuel/air mixture in the proper cylinder at just
the right time -- and this happens more than 7000 times a minute!
*How to Keep Your Volkswagen Alive --
A Manual of Step-by-Step Procedures
for the Compleat Idiot,
1976 Edition, pages 14 and 37.
Types of Ignition Systems
There are four different ignition systems you can use on a
VW:
1. The stock points/condensor system. Works OK, but the voltage at the plugs
gradually drops as the rpm increases (this happens with all points/condensor
systems) and the points will also start to "float" at very high rpm. The plugs
get about 18,000 volts. The points wear fast because they have to switch about 5
amps, and so they spark. The condensor reduces the sparking but it still happens
so the points wear out (burn). The spark also slows down the switching process,
so the coil gets a "soft" switch and the resulting plug voltage is a little less
than it could be. (The coil produces the high voltage to the plugs when the
points open and the magnetic field inside the coil collapses. The faster you can
cut the power to the coil the faster that field collapses so the better the plug
voltage).
2. The Pertronix/compufire points replacement modules. These replace the points
with a hall-effect sensor or (in some earlier models) an optical sensor. They
electronically switch the power to the normal coil, so the coil is still working
at 12v (but the elecronic switching is faster than the sparking points so coil
performance is a little better). The plugs get about the same 18-20,000 volts.
These points replacement units don't wear so your timing stays very steady and
doesn't need adjusting much.
3. Transistor assisted ignition. These use a very small
current through the points to switch a power transistor on and off (imagine the
power transistor as an electronic relay - using a small current to switch a
bigger current) and the power transistor supplies a normal 12v to the coil. But
like the Pertronix it provides faster switching than sparking points can, so
coil performance is a little better than stock - still in the 18-20,000 volts
range to the plugs though. The points last a long time as they don't spark any
more - only a tiny trigger current flows through them. These systems are not
very common these days, but will work well, and are easy to build. You could
consider these sytems as a cheap alternative (but roughly equivalent) to the
Pertronix/Compufire.
4. CDI - Capacitance Discharge Ignition. This can be triggered by 1 or 2 above,
but is not used in conjunction with 3 at all. (Consider it as a BOOSTED #3). The
CDI system has a couple of very large capacitors continously charging from a
high frequency circuit using a "toroid" (donut shaped) transformer inside the
unit (the high frequency produces the characteristic whine like a camera flash
charging up) and when the points or the Pertronix triggers it, the capacitors
dump about 400v through the coil, so you get about 40,000 volts out of it for
the plugs, rather than the normal 18-20,000v. This provides a thinner but much
hotter spark which will light a weak or rich mixture, so you get easier
starting, and you also get slightly better economy, and your plugs last longer.
And of course - if you use it with the normal points, the points will last a
long time because they are only providing a small trigger current - the
capacitors are providing the main pulse to the coil. You can open the plug gap a
little with a CDI - for a longer spark. Up to about 45thou, but if you set it at
35thou you can forget the plugs for many thousands of miles - the electrodes
with still burn away slowly, but won't go "over gapped" because you started with
a modest increase. One useful feature of POINTs fired CDIs is that they can be
used to upgrade the ignition on early VW engines and still retain the retarded
No3 ignition which is needed for the non-doghouse engines.
MSD is usually a variation of the CDI - providing a multi spark rather than a
single spark.
There are also magnetos which will fit the VW engine - these are self contained
ignition systems - no battery is needed, and are sometimes used in VW aircraft
engines.
Wisdom of Bob Hoover
Dave wrote to Bob Hoover, a well-known VW guru in
Southern California -
Bob, I need some input regarding the single vs double vacuum distributor... It's
not real clear to me which of the two distributors (single/double vacuum) is the
right one to use with my 34 PICT/3 carburetor.
I called the man at a local VW repair shop; the guy called the warehouse and
talked to them about the double vacuum distributor. They want over $300 for it
new! They asked him why he wanted to know; he told them what I had said (passing
along your advice) about the 009 and the 34 PICT being incompatible. They said
that the double vacuum distributor was made for use in California ONLY!
This shop has a rebuilt single vacuum distributor for about $90.
So once again I'm in a quandary. Do I believe a source that has proven itself
unreliable and buy the cheaper single vacuum model and hope for the best? (I'm
inclined to, as I really don't want to have to shell out over $300 for a new
distributor!)
Do you have any cogent words of wisdom? I'm getting desperate with this lousy
hesitation problem; I want to do the right thing, hopefully without breaking the
bank!
Bob Hoover responded -
1. The 34PICT's will work with ANY vacuum-advance distributor.
2. The double-canister distributors are used on engines having a very low
static-timing point to insure complete combustion at idle speeds. (The
alternative would have been using a different cam.)
3. The VW cam, valves, intake & exhaust
volume dictate a particular advance-point for proper operation, which is up
around 30 degrees BEFORE TDC and which generally is all-in by about 2500 rpm.
Above that, the same factors serve to limit the engine's output, a very
sophisticated form of rev-limiting.
4. A vacuum-advance distributor will NOT give you that much advance in a linear
fashion.
Now look at what you've got: A dictated AFTER-TDC static-timing point on an
engine whose optimum operating speed demands a firing point of about 30 degrees
BEFORE-TDC... and inherent limitations in vacuum-advance distributors which
prevent them from covering that range.
So you use a composite distributor, one having BOTH vacuum advance, which gives
the required responsiveness, AND centrifugal advance, which gives you the
desired range.
The retard side of the canister was added to insure a positive back-down of the
firing point when the throttle was closed. Otherwise, the firing point would
decay according to the speed of the engine (ie, under the control of the
centrifugal-advance system). Even then, it was an interim solution until they
could get the bugs out of the fuel injection system. (Mexican bugs are fuel
injected. Very nice, reliable system. Illegal in Ami-Rica, of course.)
If you do not see the retard function, don't use it. On a dual chamber canister
that means disconnecting the retard-signal line. (It will usually be the lowest
pick-off point on the carb.) You need to seal the lines to prevent anything
getting into the canister or being sucked into the manifold. And of course,
re-time the thing.
If you have a single-canister distributor
(or a dual-canister distributor with the retard side disabled), set your static
timing at about 7.5 degrees BEFORE TDC and drive on. Most vacuum-advance
distributors will give you about twenty degrees total advance. Check it with a
timing light by revving the engine. Tweak accordingly but don't push it too far
-- hot day, low-octane fuel, you?ll get detonation even though everything is set
to spec. I fun about 28 degrees total advance.
(In earlier messages to you and Rob I've not mentioned the initial static timing
point because I assumed the principle was understood with regard to emissions
and the carb/distributor combo.)
If you don't have a good vacuum-advance distributor, go get one. Go to a
junkyard and buy half a dozen of the things in beater condition. Remove the
vacuum canisters. If you can't find a good vacuum canister, go buy one.
(Replacements run about $25, new, Bosch, here in southern California.) Throw the
distributors in a can of oil to soak over night, then dismantle them. Be careful
to preserve the spacers and washers -- they're hard to find (I often buy a new
-009 just to get the spacers!) Match the best fitting shaft-to-housing and
reassemble the distributor using a proper number of shims and spacers to give
minimum end-play. Go drive the thing.
If you want to make it last forever, or at least longer than the 70,000 or so it
normally lasts, get rid of the points. Opening the points represents as
asymmetric load on the distributor. Opening the points is the major cause for
wear on the shaft and bushings. So get rid of them. Use a Pertronix unit. No
load on the distributor shaft. Runs concentrically. Vastly reduces the wear-rate
which is already pretty low because the distributor only turns at one-half
engine speed. (Don?t use an optically triggered unit. The Pertronix is magnetic.
The Hall effect sensor, amplifier and SCR are contained in the pick-up unit.)
Okay, so you're not a mechanic (you should be, if you want to own/operate an
orphaned, antique vehicle). A new, vacuum advance distributor costs about $90.
Roland Welhelmy bought one a couple of weeks ago from the Old VW Company in
Escondido and sent a note about it to the Type 2 mailing list. (OVW = (760)
73-7587). Give them a call, see if they'll send you one. Ditto for the Pertronix
unit, while you're at it. (It runs about $60.)
Regarding advance mechanisms: You can make a centrifugal system advance as far
as you want and at whatever rate you want. Friction and loss of spring tension
is the only problem. But with a vacuum-advance system, the thing is only linear
across a fairly narrow range, although marvelously responsive within that range.
Most cars use composite or combination systems -- a vacuum-advance to initiate
acceleration and a mechanical-advance to continue that advance to whatever
limits -- and at whatever rate -- the engineers decided upon.
But one thing you CAN'T do is stick a purely mechanical system into a VW and
expect it to be responsive to the throttle. First, you must bring about a change
in rpm, usually by feathering the throttle -- pumping a little more gas -- THEN
the advance kicks in -- and will advance as far as you want it to, depending on
what you've done to the bob-weights and springs. This is perfect for the
dragstrip, where you jack it up to three grand before you even pop the clutch,
and thereafter go flat-out thru only two gears, at most. The -009 is great for
that. Otherwise it's a piece of crap.
Personally, I think you should be driving a Toyota. Early air-cooled Volkswagens
require about ten times the annual preventative maintenance of a modern vehicle
and it must be SKILLED maintenance. If you gotta pay someone to do it, you VW is
going to cost you more than a luxury car. And if you don't do the maintenance,
you're going to have a crappy ride. And if you try to do it yourself and screw
things up. A Toyota seems like a good idea to me.
Notes on the Centrifugal vs Vacuum Controversy
Pro Centrifugal Advance -
John Muir* wrote -
Just what kind of distributor
do you have? Volkswagen has used three main types through the years: mechanical
(centrifugal) advance, semi-mechanical advance and vacuum advance. The first two
types have been the same all the way, but the vacuum advance distributor has
gone through several modifications and has been standard equipment on all models
for many years. I hate them! They are another sop to American buyers who refuse
to learn to shift a car with a little coordination. This is just a personal
beef, so forgive me. I use a straight mechanical advance distributor, called the
Porsche Type, which advances the distributor on rpm as the engine speeds up.
Most VW race cars and beach buggies use the same. It gives a very good power
curve on the VW engine.
The vacuum distributor
advances the spark based on the vacuum in the carburetor (as opposed to rpm) and
they will never make good since the principle is wrong. That, however, is what
they give you with the car. I saw a demonstration 1969 accessory car on a VW
showroom floor with a speed set-up on the engine, and guess what? Right. It has
a mechanical advance distributor on it and at o only $30.00 extra, so when you
get bread ahead, buy one for your jewel. You have to block up the hole (or
holes) in the carburetor so it doesn't leak vacuum. Vacuum leaks burn valves, if
you didn't know. Now that's out of my system.
*How
to Keep Your Volkswagen Alive --
A Manual of Step-by-Step Procedures
for the Compleat Idiot, 1976 edition, page 90
Rob Boardman says -
The 009 does often cause acceleration flat spots,
and these can usually be overcome by ensuring the accelerator pump is adjusted
for it's maximum stroke, and you might need a richer main jet in the carby.
I have heard of a couple fixes for a 34PICT and 009. One from this newsgroup
which is to pop rivet the hole in the throttle plate and the other is to go with
a bigger idle jet.
Dave wrote to Rob -
Regarding the distributor: Have you been following
the responses on the Newsgroup to the guy who put in a 009 and thought it was
wonderful? The responses are running VERY heavily in favor of the vacuum advance
dizzy. I think we did the right thing.
Rob responded -
Yes, I noticed this too. Since I found out what
they were originally designed for (hard working 1200 busses, and they also
appeared on some of the industrial engines, which work at more constant speeds),
I've been telling the story to anyone who'd listen. My main argument is that
since VW obviously ARE familiar with 009s, and didn't use them with any of the
bigger engines, they obviously felt that the engines worked better with vacuum
distributors. There were only ever two kinds of centrifugal-only, the 009 and
the VW equivalent (which I think was a 050), but they tried lots of variations
in the vacuum distributors, so the inference is that they found the 009 etc.
unacceptable, but in their inimitable style, they fine tuned the vacuum
distributors with the various engines.
Pro Vacuum Advance -
Rob wrote -
The 009s are a very common replacement distributor,
but have serious limitations when used in road vehicles, since they are
centrifugal only, and so they can't "load sense" like the vacuum distributor.
They are also a "one size fits all" distributor, which means that they are not
"ideal" for any particular engine type. They do work quite well in applications
where the VW engine is operating at high rpm and high power, for example, racing
VW engines, or powering compressors and power generators.
And when rpm is high we need more advance, and when rpm is low we need less
advance.
Fortunately, the vacuum distributor (and the combined centrifugal/advance of 74+
distributors) does a reasonable job of following these two conflicting needs.
The vacuum port on solex carburettors is placed just UNDER the main venturi,
close to where the throttle plate passes as it opens. So imagine the engine
idling. The throttle plate is nearly closed, so there is a low airspeed through
the main venturi - not much vacuum there or just under it (above the throttle
plate). The vacuum port sees very little vacuum, and the idle advance setting
prevails (7.5-10BTDC on most models).
Now open the throttle a little, so the edge of the throttle plate passes by the
vacuum port. This creates a mini-venturi with very high air speed, which creates
a lot of vacuum, so you get a shot of advance to help speed up the engine (this
effect is entirely missing with the Bosch 009 distributor, which is what causes
the "009 flat spot"). Since in a part-throttle condition you still have a high
proportion of burned gases for a low flame speed, this high advance also meets
the advance condition needed to deal with that too.
Now open the throttle right up. The
throttle plate moves away from the vacuum port (no mini venturi) and so the MAIN
venturi is providing the vacuum effect, but since the airspeed hasn't yet
increased much yet (engine hasn't yet increased rpm), the vacuum signal is lower
than part throttle, so the advance is reduced a little. Perfect for a fresher
mixture (lower proportion of burned gases with an open throttle remember?). Now
the engine rpm starts to catch up with the open throttle, so the airspeed
through the main venturi increases, vacuum increases, and the advance increases
progressively, which is just what you want for the increasing rpm, since the
crankshaft is rotating in less time so you need more advance to get that fresh
charge completely burned at the right moment.
So the vacuum distributors allow for high advance at high rpm/open throttle,
where rpm is the dominant factor; and also allows high advance at part
throttle/medium rpm, where the proportions of burnt/fresh mixture is the
predominant consideration.
"Speedy" Jim wrote -
Sounds like somebody substituted the well-known Bosch ?009) distributor. This
has centrifugal advance only. Some people swear by it. (Others swear at it!)
Lacking vacuum advance, it is slower to respond to load changes or throttle
opening and thus the hesitation. (Do check the pre-heat temp, though, as well.
My personal preference is for the stock (double vacuum) distributor, but they
are hard to find in good condition and expensive to buy new. Swap meets are a
good source. Be aware, though, that there were a dozen or more models, all look
alike.
See The Wisdom of Bob Hooveron this subject.
Dave wrote, regarding installation of the vacuum
advance distributor -
I turned the rotor to #1 and pulled the 009
distributor out. Then I set the points in the new one (double vacuum) and
slipped it in place. It's interesting that #1 is on the left side; it was on the
right on the 009. I attached the vacuum port on the silver canister to the port
on the back (back) of the carburetor with rubber tubing. Then I attached the
port on the bottom front (front) of the canister to the vacuum port on the left
side of the carburetor--rubber tubing on the ends and a piece of copper tubing
bent in the shape of a trap in the middle.
I static timed it to 5 degrees ATDC just to get in the ball park, and fired her
up. The car started with no problem. I pulled it out of the garage onto the
driveway and proceeded thru the detailed tuning -- dwell angle at 50 degrees,
timing at 5 degrees ATDC with the timing light -- then to the idle. No dice. I
tried to reduce it below 1200rpm -- wasn't having any. The engine died when I
got it down to 1000. I'm absolutely clueless.
(Dave later discovered a severe air leak around the throttle shaft in the bottom
of the carburetor into the intake manifold, which was making the fuel mixture
very lean and requiring a high idle to keep the engine running. This discovery
resolved Dave's nagging problems with hesitation and inability to properly set
the idle.)
Then I took the car out for a test drive. It's considerably better, but not
perfect. My wife said it seemed to "fweem" better to her, and it does. But it's
still a little rocky. The guy at the VW shop claims that the problem is the 34
PICT carburetor (they put it on the engine when they rebuilt it!). He says I
should go to either the 30 or 31 -- the car will never run right with the 34.
The best combination (he claims) is the 009 dizzy and the 31 carburetor. I'm
getting too much advice -- I don't know who to believe! Actually, yes I do. I
lean heavily to your advice (Rob) and that of Bob Hoover, and I will continue
down the vacuum advance dizzy path.
Dave wrote to Bob Hoover -
Thanks for the great "sermon" on vacuum vs
centrifugal distributors. It finally tipped me over the edge--yesterday I bought
and installed a rebuilt vacuum advance distributor, replacing the 009 that was
causing our '73 SB to hesitate on acceleration. The guy that sold me the new
dizzy said, "Be sure to keep the 009--you'll be putting it back on in a week!" I
don't think so--the new dizzy has virtually eliminated the hesitation problem
that has been plaguing us from day one. (There sure is a widely divided opinion
on centrifugal vs vacuum advance distributors!)
Rob wrote -
Don't forget, with the 009 distributor you normally need to run a larger main
jet, and sometimes a smaller air correction jet (I'm not sure how the
progressives are actually set up). This helps make up for the lack of vacuum,
and reduces any flat spots in acceleration, at the expense of higher fuel
consumption.
The 009 Centrifugal-Advance
Distributor --
History and Notes
Someone wrote -
Ever since I came into the VW scene (about 2 yrs)
I've been hearing people going on and on and on for the 009. Where the heck did
it come from? Was it a stock part for certain VW's? And what difference will it
make on my 1969 1300sp engine. Oh yeah, and whats that "flat spot" all about?.
Im VERY confused.
Rob responded -
VW built a lot of industrial engines (called type
122 for the 1200 and 124 for the 1600) as well as those built for the beetle
itself.
Industrial engines powering generators, compressors and such are near enough to
constant speed, so only a simple distributor was needed. So a centrifugal
distributor was developed by VW, and later by Bosch. This type of distributor
increases the amount of advance as the engine speed rises, but can not sense the
throttle position (engine load). This is fine for engines operating at constant
speeds, or at high power and high rpm (for VW racing engines for example, plus
the previously mentioned industrial engines).
When the first Type 2 (Kombi etc) vehicles came out (1954 I think), they used
the 1200 VW engine and needed reduction hubs so that the tiny engine could push
a heavy vehicle (with a top speed of about 85kmh since the reduction hubs meant
it was revving it's heart out!).
Because these engines in the Type 2 were working at high rpm and high throttle
most of their life, the VW version of the centrifugal distributor was used on
them too (but just try getting one off the line - they needed a lot of revs and
clutch slip to avoid bogging down).
Most engines in road vehicles operate at various engine
rpm and load conditions, which requires a lot of variation in the amount of
advance needed for optimum engine performance and economy. Ideally, the amount
of advance varries from about 7 degrees to about 42 degrees, depending on the
engine model and it's intended use.
So most road vehicles use vacuum sensing, or a combination of vacuum and
centrifugal, to get the best timing over a wide range of engine operations --
low throttle low rpm, low throttle high rpm, high throttle high rpm and every
variation in between.
The early beetles used single vacuum distributors (SVSA). Then in 1971 they
introduced the double advance technique -- using both rpm-related and
vacuum-related advance. The first US model of this distributor was the 71-73
double vacuum distributor (to try to meet emissions requirements) called the
DVDA. In other parts of the world a single-vacuum dual advance (SVDA) was used.
From 1974 onwards the US also went to the SVDA. The SVDA distributor works like
a high quality 009 with added vacuum advance.
These distributors are quite expensive to build in comparison with the Bosch 009
(the Bosch equivalent of the VW centrifugal distributor). So the cheap-to-build
Bosch 009 became the "one size fits all" replacement distributor, since it IS so
cheap, and it does work moderately well. But precisely because the 009 is a "one
size fits all" distributor, it is NOT ideal for most engines, and it can cause
problems for some engine/carby set-ups.
To accelerate an engine smoothly,
you need both extra fuel and an extra advance. The accelerator pump provides the
extra fuel and the vacuum distributors provide the additional advance needed.
But a 009 cannot provide any advance until AFTER the engine rpm starts to
increase (the advance starts happening at around 1200-1300 rpm) so, if the carby
is set to run a little lean (LESS fuel), you get a hesitation or "flat spot,"
which usually means the driver has to blip the throttle a time or two to get the
rpm up to the point where the 009 is starting to advance, then "feather" the
throttle (and slip the clutch) so the rpm stays high, to avoid that flat spot.
The most common technique to overcome the 009 flat spot is to replace that
"missing" advance with extra fuel - a larger main jet, max stroke on the
accelerator pump, and in some cases filling in the air-bleed hole in the
throttle butterfly. By running the engine richer than normal throughtout its
operation, the flat spot is minimised.
The earlier Solex carburettors (28PCI, 28PICT and 30PICT/1 and /2) are set to
run a little on the rich side - the VW engine actually likes around 13.8:1
air/fuel ratio, where the ideal is 14.5:1). So since these carbies are set to
run rich anyway, the flat spot is often not noticable, or can be tuned out with
minor adjustments.
But in 1970/71 the emissions problem was becoming recognised and VW changed the
jetting on the 30PICT/3 (1970 US only) and the 34PICT/3, and /4 to run the carby
leaner - closer to the ideal 14.5:1 air/fuel ratio (the California 34PICT/4 used
especially lean jetting and a throttle positioner to ensure that the throttle
closed slowly after you lifted your foot off the pedal).
So with this leaner running carby
set-up, the 009 flat spot becomes a real issue.
You'll hear most complaints from folks who use the 34PICT/3, 34PICT/4 or the
modern equivalent for the smaller carbs - the Brosol H30/31 (which is almost
identical to the 1970 30PICT/3) - all of which normally come with lean jetting.
Another issue with the 009 is the limited maximum advance. The vacuum
distributors can run up to about 40-42 degrees under the right conditions (light
throttle and medium speeds for example) and this helps fuel economy. But if you
maintained that much advance with a full throttle and low/medium rpm, the engine
would ping/detonate, a problem which can destroy an engine if not corrected. The
reason is rather technical, but is mainly related to the amount of residual
exhaust gases which are left in the cylinder compared to the incoming charge.
There is always SOME residual gas, since there's a head space above the
cylinder. At part throttle there is a proportionally larger amount of burned
gases in comparison to the fresh stuff (throttled fresh mixture but same head
space of burned gasses). At full throttle there's a lower proportion of burned
gases because you are letting in MORE fresh mixture for the fixed volume of head
space. This "contamination" of the fresh mixture alters the flame speed (the
time it takes for the fuel/air mixture to burn) so open-throttle needs less
advance (burns faster) and part-throttle needs more advance (burns slower) at
any particular rpm.
Incidentally, this is part of the reason
why the low compression 1200s need more advance - usually 10BTDC compared to 7.5
BTDC for most 1500/1600s. Low compression means more head space (compared to the
cylinder volume), and so there is more contamination of the fresh charge
throughout the rpm range, and that means a little more advance is needed so all
the fuel is burned just as the piston starts it's descent.
There is an rpm-related issue, too. As the engine rpm increases, the spark needs
to occur sooner (more advance) to make sure the maximum pressure on the piston
occurs just as it starts its descent.
The vacuum distributor senses throttle position, so if you floor the throttle at
low-medium speeds, the distributor is able to "back off" the advance until the
engine speed catches up with the new throttle position (slowly allowing the
extra advance back in as the rpm/airflow rises). The 009 can't do this, so it
HAS to be set to "worst case," which is between 28 and 32 degrees at 2500-2600
rpm (which is why we set the 009 at 3000rpm - to make sure that all the advance
is present).
Since the 009 has been limited to 28-32 degrees compared to the vacuum
distributor's 40-42, it's actually UNDER-ADVANCED for a lot of driving
conditions, and this means worse fuel economy. And because you need to set the
carby to run rich to reduce the flat spots, fuel economy suffers even more.
Because the 009 is built very cheaply, the total amount of advance varies from
one to the next. This means that when setting the 009, it's important to set it
at max rpm, not idle, since the max advance is much more important for most
engine conditions. Always use as much of the 28-32 as the engine can take
without pining/detonating, as this will reduce any flat spots just a little, and
also help fuel economy just a little. If it still pings at 28 degrees, always
use a higher octane fuel. NEVER use less than 28 degrees because it means the
engine is seriously under-advanced at higher rpm and will run hotter than it
needs to, and fuel economy will suffer as well.
In the heavier-bodied Kombi/Bus and Karmann Ghia vehicles, you might need to
limit the max advance to the 28-30 degree range. These engines are less likely
to tolerate the 32 degree maximum, as they are driven with more throttle to
accelerate the heavier body.
Once you have determined the maximum advance which works well for your 009, you
can then measure the idle advance (which will probably be between 5 and 10 BTDC
but might be outside that range). If you want to, you can then use THAT setting
for THAT 009 distributor to set it at idle or static.
So you can see that the 009 distributor is NOT ideal, but it will work. For best
performance under all engine operating conditions, we recommend using a vacuum
distributor.
Hope all that makes sense.
There are Tune-up Articles on our Web site which include info on both vacuum and
009 distributor settings.
Rob wrote -
My Bug is telling me that it needs a
little TLC -- just a slight tendency to run rough at idle. I'll bet it's a
"hill" growing on the points, a common problem with mine. I keep a "points file"
(like a flat nail file) handy for just this purpose. If it goes off between oil
changes (when it gets looked at each time), a few gentle rubs with the file by
pushing them open when they are closed -- off the cam -- and letting the points
spring hold the two sides of the points against the file. About two minutes and
it's done. Emery paper works too -- but since the stuff is non metallic,
anything left behind will act as an insulator, which occasionally causes it not
to fire until you pull something else between the points and wipe them clean.
The points file, being a metal file, doesn't have this problem.
The "hill" which grows between the points has the effect of reducing the advance
-- sparking later -- and if left to get too bad it will cause it to "miss" the
occasional spark altogether.
That is certainly one advantage of the electronic ignitions - no wear on the
points, or eliminating the points altogether, so there is no wear on the rubbing
block either.
Operation of the Vacuum Lines
Dave wrote to Rob regarding the
vacuum lines on a dual vacuum distributor
-
I've never understood completely which vacuum line went where. I think I've got
the vacuum lines hooked up backwards! Let me make sure I have this straight:
• The MAIN vacuum line attaches to the port on the vacuum chamber at the rear
(actually mine comes out of the side pointing toward the fuel pump, but that's
okay) and goes to the vacuum port on the left side of the carby under the
stepped cam. This is the line that is metal and has the dipsy-doodle fuel
condensation trip in it.
• The RETARD vacuum line attaches to the port on the front (front) bottom of the
vacuum chamber and goes to the port on the rear of the carburetor, just to the
right of the throttle return spring.
~~~
Retard Line
Question -
Is there a way to determine whether
the retard vacuum line is inoperative?
Rob responded -
Yes -- take the cap off the
distributor and suck on each of the lines in turn. You should see the points
plate move in opposite directions. The retard line will only retard a little of
course, compared to the main vacuum's advance.
Question -
If the retard vacuum line is
malfunctioning, what is the fix?
Rob responded -
First see if the hole in the
carburetor is clear -- put the vacuum line back on it and blow from the dizzy
end to see it you get air through. If it's good, the most likely cause is a
broken/leaking vacuum chamber on the dizzy. The retard line only works (when
it's working) at idle anyway, so it's less critical than the (working) advance
line.
The main vacuum line gets quite a lot of vacuum with the engine running, and may
cope with a small leak, but I think the retard vacuum probably operates at a
lower pressure difference (engine idling anyway), so would be more susceptible.
You can check for a leaky diaphragm by sucking on the main vacuum line, then
block the line with your tongue and see if the points plate stays put. If it
slowly moves back then you have a leak.
If you do end having to replace the vacuum chamber, they are pricey (here they
cost more than a whole 009), and (on the single vacuum units like mine anyway)
you have to check for a number on the vacuum operating arm inside the dizzy (the
pushrod). This identifies the exact vacuum chamber for that distributor (there
are several versions at least for the single vacuum units).
Advance Line
From Rob -
Try this... put the timing light on
it and get is up to a steady speed where you see some advance but not all of it
say 1500-2000. Now blip the throttle open and let it go so the revs don't change
much but the load does. If the vacuum line is operating at all you should see
the advance change momentarily then return to whatever it was. If the advance
vacuum line is not working, the advance should stay reasonably steady -- only
changing with the revs. If this is the case, the dizzy is definitely a dual
advance (vac/centrifugal) operating like a 009 (centrifugal only), and this
would explain the hesitation you are still getting. These dizzies are supposed
to provide the best of both worlds for the VW if you can get it working right.
~~~
Overall Operation
Dave wrote -
We went out and conducted the test
you suggested this evening. Here are the results:
1. Sucking on the main advance line alone products no movement in the points
plate (however, the spark DOES advance with increasing RPMs, as we have shown
with the timing light).
2. Sucking on the retard line alone moves the plate clockwise.
3. Sucking on both lines (advance first, then retard and holding suction on
both) produces no discernible effect.
We have already established that this distributor is a combination
centrifugal/vacuum advance model.
I hope these results mean something to you that you can then share with us so we
can improve the around-town performance of this car.
Rob responded -
You have said that the retard line
DOES work (that's the front line - nearest to the distributor body). So since
the engine is off when you do it, then contrary to John's reply, it HAS to be
retarding from neutral.
And there is only a tiny amount of suction in the advance line at idle, so how
is the retard line supposed to be "only working to reduce the main advance".
That doesn't make sense to me. Sure the two vacs work against each other as you
open the throttle - the retard vac drops away because it works at the edge of
the throttle plate which is now moving away (opening), and at the same time the
airflow through the main carby venturi is increasing which increases the main
vac, so the retard drops out and the main vac pulls in some advance.
Dave wrote -
So it is my understanding that the
retard line works to pull in retard first, then the main vacuum takes over as
you open the throttle.
Rob responded -
On my vacuum-only dizzy, the plate
moves counterclockwise to produce advance (the vac arm pulls outwards). The
retard line pushes the arm inwards and rotates the plate clockwise (same
direction as the rotor moves). The RETARD pipe on the canister is the FRONT one
- nearest the distributor body. The ADVANCE line is on the REAR (outer) side of
the canister.
Another test to check it all out -
Try running the engine at 3000-3500 and
check the timing. It should be AT LEAST 30 degrees or more (30 degrees if only
the centrifugal is working - more if the vac advance is working too). If it's
less than 30 degrees, disconnect both vac lines at the carby and plug them, then
adjust the timing for 30 degrees at 3000rpm (this means you are setting it using
just the centrifugal advance), then reconnect both vac lines.
Now drop the revs back to idle and look at the timing again. Is it 5ATDC or
thereabouts? If so, the retard vac line is working OK. And if it is working, as
you gently open the throttle with the timing light still on, the timing should
change rapidly from 5ATDC to some positive figure as the retard line stops
working.
But if its somewhere from 0 to 10BTDC at idle, my guess is that it's the RETARD
line which is not working. I say 0-10 because I don't know exactly what the
"neutral" plate position is on these dizzies.
This is just a test set-up, and I haven't tried it myself as I don't have the
same distributor, but it might help determine which vac line is actually working
and which isn't.
You'd need to re-time the engine properly after doing this test (5ATDC at idle
with vac line properly connected.)
Dave asked, regarding disconnect of the vacuum hose(s) during timing -
The manuals don't clarify which end of the hose is to be disconnected from the
distributor and plugged -- the point is to keep the carburetor from sucking air.
Right?
Rob responded -
Precisely. The aim is two fold:
1. Stop the advance plate from moving so you can set the 7.5BTDC idle unaffected
by any vacuum. Plugging the distributor end of the vac line is irrelevant at
this point -- it's inoperative anyway.
2. Prevent the carby from sucking air through the vac line so it idles evenly
whilst making the idle adjustment. So you pull the vac line off and plug the
carby end. The carby creates the vacuum, the distributor uses it.
It doesn't matter how the carby's plugged ( on the carby on the other end of the
vac line) so long as it's the carby which is plugged, not the distributor.
Dave wrote -
The book is not specific -- it just
says "plug the line". And so I did -- on the wrong end!
Rob responded -
A nice laugh. That's what we are trying to do with the Joe Shadetree aren't we
-- avoid ANY ambiguity.
A final thought from Rob -
If I ever need to replace my
distributor, I'll probably be going for one of these SVDA types too. I suspect
it will work just a little better than the vac-only unit I have at present. The
only concern I have with them for my car is that the rate of centrifugal advance
(the 009 part of it) may be slightly different to the vac-only rate of advance
at each point in the rev range, which may change the engine acceleration
characteristics a little, since it's a single port 1600, with different head/gas
dynamics to the tp1600. And the 30PICT/2 carby produces a different flow rate
through the venturi than the larger throat 34. It will be interesting to find
out if any difference is noticeable.
Vacuum Distributor Test
To determine for sure which vacuum line is working and
which isn't:
1. Put the timing light on and rev the engine up to a steady spead (1500 2000
rpm). Then 'blip' the throttle open and let it go so that the revs don't change
much but the load does. If the advance vacuum line is working, I should see an
immediate change in the advance, before the engine revs change much, and then a
rapid change back again as the throttle is released. If the advance vacuum line
is NOT working, there will only be a steady change as the revs increase the
advance won't 'blip' with the throttle movement itself.
To put it another way, if the engine revs alter by say 500rpm as I 'blip' the
throttle, I should see a timing change of maybe 2 3 degrees caused by the
centrifugal advance. But if the vac line is working, you should see it rapidly
advance by maybe 8 10 degrees as the throttle arm is moved.
2. Then run the engine at 3000 3500 and check the timing. If my theories (and
Rob's) are correct, It should be AT LEAST 30 degrees or more (30 degrees if only
the centrifugal is working more if the vac advance is working too).
3. If it's less than 30 degrees, then I'll disconnect both vac lines at the
carby and plug them, then adjust the timing for 30 degrees at 3000rpm (this
means setting it using just the centrifugal advance), then reconnect both vac
lines.
4. Then drop the revs back to idle and look at the timing again. It should be
5ATDC or thereabouts. If so, the retard vac line is working OK. But if its
somewhere from 0 to 10BTDC at idle, then I would guess is that it's the RETARD
line which is not working.
5. Having confirmed that the retard vac line is working, then I will gently open
the throttle with the timing light still on the timing should change rapidly
from 5ATDC to some positive figure as the retard line stops working.
6. Re time the engine properly after doing the test (5ATDC at idle).
Distributor Questions and
Answers
All responses are from Rob Boardman
unless otherwise indicated.
Question -
Ever since I came into the VW scene
(about 2 yrs) I've been hearing people going on and on and on for the 009. Where
the heck did it come from? Was it a stock part for certain VW's? And what
difference will it make on my 1969 1300sp engine. Oh yeah, and what's that "flat
spot" all about?. I'm VERY confused and I hope you fellow fweemers can sort it
out for me (and other newcomers).
Response -
VW built a lot of industrial engines
(called type 122 for the 1200 and 124 for the 1600) as well as those built for
the beetle itself.
Industrial engines powering generators, compressors and such are near enough to
constant speed, so only a simple distributor was needed. So a centrifugal
distributor was developed by VW, and later by Bosch. This type of distributor
increases the amount of advance as the engine speed rises, but can not sense the
throttle position (engine load). This is fine for engines operating at constant
speeds, or at high power and high rpm (for VW racing engines for example, plus
the previously mentioned industrial engines).
When the first type2 (Kombi etc) vehicles came out (1954 I think), they used the
1200 VW engine and needed reduction hubs so that the tiny engine could push a
heavy vehicle (with a top speed of about 85kmh since the reduction hubs meant it
was revving it's heart out!).
Because these engines in the type2 were working at high rpm and high throttle
most of their life, the VW version of the centrifugal distributor was used on
them too (but just try getting one off the line - they needed a lot of revs and
clutch slip to avoid bogging down).
Most engines in road vehicles operate at
various engine rpm and load conditions, which requires a lot of variation in the
amount of advance needed for optimum engine performance and economy.
So most road vehicles use vacuum sensing, or a combination of vacuum and
centrifugal, to get the best timing over a wide range of engine operations.
The early beetles used single vacuum distributors; there is a version of double
vacuum distributor (for emissions reasons) for the 71-73 beetles in some
countries only; and from 74 onwards VW used a combination distributor - like a
009 with added vacuum advance.
These distributors are quite expensive to build in comparison with the Bosch 009
(the Bosch equivalent of the VW centrifugal distributor). So the cheap-to-build
Bosch 009 became a sort of "common" replacement distributor, since it IS so
cheap, and it does work (sort of). But it's a "one size fits all" distributor,
so it's NOT ideal, and it can cause problems for some engine/carby set-ups.
To accelerate an engine smoothly, you need both extra fuel and a shot of
advance. The accelerator pump provides the extra fuel and the vacuum
distributors provide the additional advance needed. But a 009 cannot provide any
advance until AFTER the engine rpm starts to increase (actually from about
1200rpm) so, if the carby is set to run a little lean (LESS fuel), you get a
hesitation or flat spot, which usually means the driver has to blip the throttle
a time or two to get the rpm up to the point where the 009 is starting to
advance, then "feather" the throttle (and slip the clutch) so the rpm stays
high, to avoid that flat spot.
The most common technique to overcome the 009 flat spot is to replace that
"missing" advance with extra fuel - a larger main jet, max stroke on the
accelerator pump, and in some cases filling in the air-bleed hole in the
throttle butterfly.
The earlier Solex carburettors (28PCI, 28PICT and 30PICT/1 and /2) are set to
run a little on the rich side - the VW engine actually likes 13.8:1 air/fuel
ratio, where the ideal is 14.5:1). So since these carbies are set to run rich
anyway, the flat spot is often not noticeable, or can be tuned out with minor
adjustments.
But in 1970/71 the emissions problem was becoming recognised and VW changed the
jetting on the 30PICT/3 (1970 US only) and the 34PICT/3, and /4 to run the carby
leaner - closer to the ideal 14.5:1 air/fuel ratio (the California 34PICT/4 uses
a main jet which is about 6 sizes smaller than "normal"!).
So with this leaner running carby set-up, the 009 flat spot becomes a real
issue.
You'll hear most complaints from folks who use the 34PICT/3, 34PICT/4 or the
modern equivalent for the smaller carbs - the Brosol H30/31 (which is almost
identical to the 1970 30PICT/3) - all of which normally come with lean jetting.
Your 1969 1300 with 30PICT/2 carby is one of the older variety carbies with
slightly richer settings so you would not notice the 009 flat spot so much (if
at all).
Another issue with the 009 is the limited maximum advance. The vacuum
distributors can run up to about 40-42 degrees under the right conditions (light
throttle and medium speeds for example) and this helps fuel economy. But if you
maintained that much advance with a full throttle and low/medium rpm, the engine
would ping/detonate. The reason is rather technical, but is mainly related to
the amount of residual exhaust gases which are left in the cylinder compared to
the incoming charge. There is always SOME residual gases, since there's a head
space above the cylinder. At part throttle there is a proportionally larger
amount of burned gases in comparison to the fresh stuff (throttled fresh mixture
but same head space of burned stuff) - at full throttle there's a lower
proportion of burned gases because you are letting in MORE fresh mixture for the
fixed volume of head space. This "contamination" of the fresh mixture alters the
flame speed (the time it takes for the fuel/air mixture to burn) so open
throttle needs less advance (burns faster) and part throttle needs more advance
(burns slower) - at any particular rpm.
(Incidentally, this is part of the reason why the low compression 1200s need
more advance - usually 10BTDC compared to 7.5 BTDC for most 1500/1600s). Low
compression means more head space (compared to the cylinder volume), and so
there is more contamination of the fresh charge throughout the rpm range and
that means a little more advance is needed so all the fuel is burned just as the
piston starts it's descent.
The vacuum distributor senses throttle position, so if you floor the throttle at
low-medium speeds, the distributor is able to "back off" the advance until the
engine speed catches up with the new throttle position (slowly allowing the
extra advance back in as the rpm rises), but the 009 cant do this, so it HAS to
be set to "worst case" which is between 28 and 32 degrees at 25-2600+rpm (which
is why we set the 009 at 3000rpm - to make sure that all the advance is
present).
Since the 009 has been limited to 28-32 degrees compared to the vacuum
distributor's 40-42, it's actually UNDER-ADVANCED for a lot of driving
conditions, and this means worse fuel economy. And because you need to set the
carby to run rich to reduce the flat spots, fuel economy suffers even more.
Because the 009 is built very cheaply, the total amount of advance varies from
one to the next. This means when setting the 009, it's important to set it at
max rpm, not idle, since the max advance is much more important for most engine
conditions. Always use as much of the 28-32 as the engine can take without
pining/detonating, as this will reduce any flat spots just a little, and also
help fuel economy just a little. If it still pings at 28 degrees, always use a
higher octane fuel, NEVER use less than 28 degrees because it means the engine
is seriously underadvanced at higher rpm and will run hotter than it needs to.
Once you have determined the maximum advance which works well for your 009, you
can then measure the idle advance (which will probably be between 5 and 10 BTDC)
and you can then use THAT setting for THAT 009 to set it at idle or static if
you want to.
So you can see that the 009 is NOT ideal, but it will work. For best performance
under all engine operating conditions, you need a vacuum distributor.
Hope all that makes sense.
There are tune-up articles on our web site which include info on both vacuum and
009 distributor settings.
Question -
I'm having a problem with my car.
The other day I went down and washed my engine. Now it won't start. I used my
manuals and the coils still strong, the distributors working. I pulled the spark
plugs and replaced them all. I tested them out of the engine and they are
sparking just fine. So now I'm questioning the fuel system. The pumps working
fine. I pulled the air cleaner but no gas is coming from the carb into the
throat. (I'm guessing the gas comes from that pipe from the top of the carb once
the air cleaner is removed, the one above the first butterfly valve) I have a
brand new battery and the starter is turning the engine over. Also gas is coming
out of the bottom of the engine from unknown location. I tried to pore a little
gas into the carb but no firing... How could washing the engine screw this up so
bad! I could use some help.
Response -
VWs hate wet distributors and will
leak the spark to ground very easily. At night you can try getting a friend to
crank the engine and look for sparks over the dizzy cap (interesting when you
see this - quite pretty!). Try removing the centre electrode from the cap and
wiping around it with a dry cloth/tissue. Same thing with the coil - make sure
the area around the centre connector is very clean and dry. Replace and test for
spark with the spark plug end of one wire and a spare plug - held against the
engine casing (you'll need a friend to crank the engine a couple of times). The
spark is much easier to see in the shade or at night. Be very careful you don't
tangle with the fan belt/pulleys when working near a turning engine.
If no spark, also check for 12v at the
coil (on the + side). If you don't have a voltmeter, just use any 12v globe and
connect to the + side of the coil and to ground (engine case), and turn the
ignition on. If the light glows, then the coil is getting power. If your car has
reversing lights, this test can be done by putting the car in reverse and
turning on the ignition, since the reversing lights get there power from the 12v
connector on the coil (the 66 didn't originally have reversing lights though).
Also try removing the cap and wiping it inside with a dry cloth - even a tiny
mist of water there will cause problems. If there IS a little moisture inside,
dry the points too (not as sensitive as the cap since the points only see 12v,
and the cap sees 18,000 volts), but still useful sometimes to dry the whole
thing with a hair drier etc if needed. You could also try spraying copious
amounts of WD40 around to disperse the water, but this will cause a mess in
itself, and a dust trap later on.
Question -
(My engine) idles perfectly, if you
step on the gas, the engine coughs and sputters before revving up. Could that be
caused by the distributor?
Response -
The distributor, or a combination of
distributor and the carby.
Question continued -
I spent all day messing with the
mixture screw. It does it at every setting from as far in as the screw can be
while still running to the screw practically falling out of the carb.
Response -
Do you get any variation in the idle
when you play with the screw? If not then the idle jets themselves may be
blocked.
Question continued -
So I'm pretty sure the problem isn't
the mixture. I just changed the distributor from a 009 to a stock vacuum
advance, could the vacuum advance distributor be crap and be causing this
problem?
Response -
It's possible. You can check the
vacuum arm operation very easily - take the cap off the dizzy so you can see the
points plate, take the vacuum line off the carby, and suck on it. The points
plate should move and then stay put if you cover the tube with your tongue. If
it drifts back the diaphragm is holed and it won't pull in advance like it
should (not as fast anyway).
I forget exactly what carby you had on too - the vacuum distributor does not
need as rich a mixture ( can use smaller jets) compared to the 009, but if the
richer ones are in their, then you should not get the hesitation anyway. You
have the vacuum line connected to the port on the left side of the carby - just
above the throttle arm?
You should have the idle set at 10BTDC (static) for the vacuum distributor on
that engine.
Oh - and I presume the vacuum canister is the old variety, with an adjusting nut
in the middle of it? There are several types of vacuum canister, to suit the
different vacuum signals from different sized carburettors. I'm no expert on the
36hp engine, but I know it had an adjustable vacuum diaphragm.
Have you checked the operation of the vacuum canister? Remove the vacuum pipe
from the left side of the carby (the vacuum point just above the throttle shaft
is the advance vacuum line) and with the top off the distributor, suck on the
vacuum line (still connected to the vacuum canister). You should see the vacuum
arm move and it should stay put if you then cover the vacuum pipe with your
tongue. If it doesn't move the vacuum canister is shot of sticking, and if it
drifts back when blocked then the diaphragm is holed - it will still work (sort
of) but will then stumble as you try to accelerate.
If your car has a single vacuum canister (only one vacuum line to the canister
on the carby), then as I said above this must be connected to the left side
vacuum port. Any vacuum ports on the rear (rear of car) of the carby must be
plugged - they are not used with single vacuum distributors (double vacuum
distributors were used mostly in the USA and DO use the rear vacuum ports on the
carby).
Question -
The cam duration is marginally more
than stock, will the distributor advance correctly?
Response -
It should be OK, since as you say
you will have a larger capacity feeding through the same carb - you should have
a good airflow for good vacuum signal. With the SVDA type distributor you have,
the vacuum is only providing about 8 degrees of the advance and the centrifgual
part the other 30 degrees or so, so a fractional difference in the rate of
advance should not be noticable.
It's certainly another reason for sticking to a mild cam though - too much
overlap and you won't get that early vacuum advance kicking in properly.
Bob Hoover wrote -
VW distributors are not well sealed.
There is always some amount of oil vapor inside the unit. Combined with the
carbon granules that wear off the central button in the distributor cap,over
time this obscures the IR pickup on the optical sensor and results in misfires.
Someone responded -
Of course, VW did include a dust
shield in their later distributors which would help the carbon granule problem
immensely. The Haynes and Chilton's manuals both show a plastic shield which
sits on the rim of the distributor body, held in place by the cap. The hole in
the middle is hardly larder than the shaft of the rotor, and any carbon granules
from the carbon button would have a hard time finding their way through the gap
in between.
However, my own distributor aside, I have yet to see *any* aircooled VW with its
shield still in place (though admittedly, I haven't looked under *that* many
distributor caps ) They seem to fall victim to the "runs fine without it there,
so throw it out" mentailty at some point in most cars' histories. Watercooled
VW's have similar distributors, and guess what? They have the same dust shield
too. In fact, the dust shield, distributor cap, rotor, and anti static shield
from many Watercooled VW's fit just fine on the later aircooled distributors.
The caps I saw on the watercooled VW's at the local salvage yard were the exact
same part number as the cap I already had on my distributor. The one rotor I
brought back as a sample was somewhat different though. Fits just fine, but has
a resistance of 1K instead of 5K (this offset partly by the fact that extra
resistance was designed into the spark plug wire connector at the distributor
cap, and more by the factory use of carbon wires rather than copper). John C has
mentioned that the stock rotor sometimes dies over time with the extra energy
from a CDI. I think one of the 1K watercooled rotors may survive better, and
save the trouble of digging out the epoxy and soldering in a chunk of brass as
John suggests.
Dave wrote -
I'm guilty! I'm a heretic!! I did
the unthinkable! I put the 009 dizzy back in!
I static timed it and took it out for a test drive. Pretty good -- better than
the vacuum dizzy, I have to say. So I backed it into and slapped the timing
light on it. It was just a tad advanced, so I turned the dizzy back just a titch.
Revved it up, and right up to my 30-32 degree mark it went. Took it out again --
the car has NEVER run better!
Rob responded -
OK, so now we know there probably IS
a fault in the double vac unit. So is it the retard vac in the canister, or the
points plate sticking? I guess you could check the points plate by disconnecting
the vac actuating arm and seeing if the plate moves freely through it's range.
If so, it must be the canister. THIS should be findable (new of course -- second
hand would be just asking for the problem again). I can buy vac canisters over
the counter here (pricey but available), so they MUST be available there
somewhere.
You could also try using the vac unit as a single vac, and see if that gets rid
of more of the hestitation. It still may not be perfect of course, because the
carby tuning is really set up for the idle retard, but it might come very close.
Dave wrote -
I can go around a corner in second
gear with out even touching the clutch -- not even a hint of hesitation. It
still revs a little before taking hold ...
Rob responded -
That's the 009 centrifugal only
advance for sure.
Dave wrote -
My conclusion from all this is that
my vacuum distributor is defective. That's the only conclusion that makes sense,
because I remain convinced that the double vac dizzy is the one that should be
used with the 34-PICT/3 carby. Maybe I'll be able to fix it, like Bob Hoover
recommends, but junked VWs are almost impossible to find around here.
Rob responded
- As I said, if you can get a new vac canister, and the points plate works OK,
that may be all you need. Alternatively, Bob Hoover says the spacing washers
from a 009 make dandy spacing washers to fix the free play in vacuum units.
Dave wrote
- Well, I did it. I ordered a Single Vacuum Dual Advance (SVDA)distributor
...<.P> I backed the Bug into the garage and pulled the 009 distributor out of
it. Then I put the new SVDA dizzy in -- a VERY tight fit. I had to remove the
bracket and then gently persuade it over the seal and onto the shaft, then push
and push to get the shaft down into the hole. This is good -- we certainly
shouldn't be getting anymore oil leakage! How some ever -- I'm confused. The #1
notch on the rim of the distributor ends up being at about 1 o'clock, which I've
never heard of before -- it's supposed to be at 5 o'clock.
Rob responded
- Yes that's correct -- should be about 5
o'clock. But I seem to remember you saying the 009 had #1 cylinder in the 1
o'clock too, so it may be that the camshaft has been inserted wrong. If this is
the case it shouldn't matter so long as the plug leads are fitted appropriately.
Dave wrote
- I went ahead and attached the wires that way -- 1-2-3-4 around the distributor
counterclockwise (opposite the way it runs).
Rob responded -
Firing order is 1432, so if you
start at 1 o'clock, the connections on the dizzy would be --
2 1
0
3 4
I think that's the same as you described above.
Dave wrote -
Then I static timed it, started it
up and timed it with the timing light (the static timing was right on). It purrs
like a kitten in the driveway, but it doesn't run any better on the road -- in
fact, I think it's worse -- it always hesitates when I goose it and when I let
out the clutch after turning a corner.
Rob responded -
Could just be the tuning is wrong
for the new distributor -- other than that I'm not sure.
Dave wrote -
There's got to be something
basically wrong here that I'm overlooking. The fact that #1 is at 1 o'clock on
the distributor is weird and makes me very suspicious. I think that the firing
sequence is all screwed up, but I'm not smart enough to know how to test it and
correct it. I suspect I should pull the #1 plug and make sure it's at TDC when
the notch on the pulley lines up with the split in the crankcase -- THEN put the
distributor in and see where the rotor points. I think I'm 180 degrees out of
phase or something.
Rob responded -
That's possible. Yes -- pull the #1
plug and the right rocker cover. Find TDC with BOTH valves shut (loose) -- this
will be the firing stroke for #1, and see where the rotor is pointing. That will
be your starting point. Once you have #1 the others will follow the correct
sequence.
Dave wrote -
It seems to be possible to put the
drive shaft back in any old way, as long as it engages the crankshaft gear. That
would explain a LOT!
Rob responded -
Could just be the tuning is wrong
for the new distributor.
Dave wrote -
Could you be just a little more precise? What aspect of the "tuning" may be
wrong? What should I experiement with? Different point settings? The timing?
Idle?
Rob responded -
I was thinking of the carby settings
-- it runs better with richer settings for the 009, maybe too rich for the
single vacuum dizzy? Could try a little less squirt on the accel pump, and
adjusting the volume screw (smaller one).
Dave wrote to John Connolly -
I have successfully installed the
SVDA Distributor you sent me, and the car is running very well.
However, I have a question -- I am confused by the fact that the notch for the
#1 cylinder is at about 1 o'clock on the distributor rim -- according to the
manuals it's supposed to be at about 5 o'clock. I have verified that the #1
piston is at TDC with the pulley at the TDC mark and the rotor pointing to the
notch on the distributor rim. The valves are closed, so I know that #1 is at TDC.
John responded -
That distributor came out of a type
4 engine, that's all. Since there is no retard on #3, you just wire it up. Make
SURE you don't have plug wires crossing one another, that's asking for trouble.
Dave wrote -
My distributor driveshaft is a
little bit cockeyed, but I don't think that should make a difference as long as
the spark plug wires are attached properly (counterclockwise from the notch, 1 2
3 4; firing order 1 4 3 2).
I would appreciate any advice -- this situation seems a little strange (though
the car is running better than it ever has before).
Dave wrote to John -
I found that 1 & 2 and 3 & 4 were
crossed; I corrected that, and it DID make a difference. I was not aware that
that could be a problem, and I doubt that many VW owners are.
John responded -
Now I need to convince you to the
Pertronix and CDI. Next step up in the running good process.
Dave wrote -
I've been interested in the
Pertronix system for some time. Is there some place on the Internet where I
might learn more about it; e.g., performance, installation, etc.?
John responded -
Read the tech articles on our site (Aircooled.Net),
especially the bolt on mods (the first one). They are easy to install (about an
hour total).
Rob wrote -
I had a chat with my mechanic friend
at Intervolks this morning. Apparently we can't get single vac dizzies any more
in Aus, although replacement vac canisters can still be obtained (just over
$50). the 009 here cost about $130, which is about right with exchange rates and
freight. He didn't know the SVDA was available anywhere, so I told him about
aircooled.net. He's using a 009 on his 69 1500 with 30PICT carby, says it runs
great after altering the jets in the carby. We know that story don't we! As we
know, the 30s cope with the 009 better than the 34s anyway.
Someone wrote -
The cam duration is marginally more than stock, will the distributor advance
correctly?
Rob responded -
It should be OK, since as you say
you will have a larger capacity feeding through the same carb - you should have
a good airflow for good vacuum signal. With the SVDA type distributor you have,
the vacuum is only providing about 8 degrees of the advance and the centrifgual
part the other 30 degrees or so, so a fractional difference in the rate of
advance should not be noticable. It's certainly another reason for sticking to a
mild cam though - too much overlap and you won't get that early vacuum advance
kicking in properly.
Someone wrote -
I guess I should have said it idles
perfectly, if you step on the gas, the engine coughs and sputters before revving
up. Could that be caused by the distributor?
Rob responded -
The distributor, or a combination of
distributor and the carby.
Question -
I spent all day messing with the
mixture screw. It does it at every setting from as far in as the screw can be
while still running to the screw practically falling out of the carb.
Response -
Do you get any variation in the idle
when you play with the screw? If not then the idle jets themselves may be
blocked.
Question continued -
So I'm pretty sure the problem isn't
the mixture. I just changed the distributor from a 009 to a stock vacuum
advance, could the vacuum advance distributor be crap and be causing this
problem?
Response -
It's possible. You can check the
vacuum arm operation very easily - take the cap off the dizzy so you can see the
points plate, take the vacuum line off the carby, and suck on it. The points
plate should move and then stay put if you cover the tube with your tongue. If
it drifts back the diaphragm is holed and it won't pull in advance like it
should (not as fast anyway).
I forget exactly what carby you had on too - the vacuum distributor does not
need as rich a mixture ( can use smaller jets) compared to the 009, but if the
richer ones are in their, then you should not get the hesitation anyway. You
have the vacuum line connected to the port on the left side of the carby - just
above the throttle arm?
You should have the idle set at 10BTDC (static) for the vacuum distributor on
that engine.
Oh - and I presume the vacuum canister is the old variety, with an adjusting nut
in the middle of it? There are several types of vacuum canister, to suit the
different vacuum signals from different sized carburettors. I'm no expert on the
36hp engine, but I know it had an adjustable vacuum diaphragm.
Ignition Wires and Spark Plugs
NOTE:
Regarding the "reading" of spark plugs, please see the
Spark Plug article.
Misfiring
A question is often asked about why the
engine “shakes” at idle.
Rob gives several possible reason for the
“shakes” -- those pertinent to wires and plugs are as follows -
A wobbling engine
usually means one cylinder is not firing properly.
Here are some
things you can check -
1.
Spark Plugs -- Sometimes a spark plug will not work well as idle
but will work OK when the engine is running faster. Pertonix Ignition may help,
as the Pertronix ignitor usually makes better sparks at low speeds than the
standard ignition.
2.
Spark Plug Wires -- Make sure the spark plug wires are not
shorting out. You may be able to see this arcing on a dark night with the engine
running. If you have Pertronix ignition, a hotter spark is produced that will
jump through old spark plug wires.
3.
Low Compression -- (See our discussion of
engine diagnostics for a compression test procedure.)
4.
Carburetor Shut-Off Solenoid -- (See our discussion of
engine wobble for a check of the shut-off solenoid.)
5.
Air Leakage Into the Intake Manifold -- (See our
air inleakage discussion.)
Test for Cylinder Mis-Firing -
(Sometimes called
a “power balance” test.) This test provides a good indication of how much each
cylinder contributes to the overall power output of the engine. In addition, it
also isolates which cylinders contribute little to manifold vacuum.
You can perform
this test at home on any VW engine except those with electronic ignition. If
there is a suspected burned valve or other major problem, this quick and easy
test will indicate which cylinder it is. Because VWs have only four cylinders, a
faulty one will show up relatively quickly.
To perform a cylinder mis-firing test -
1. Remove all the spark plug leads from the spark plugs.
2. Set the leads lightly back on the tops of the spark plugs. This will enable
the lifting of each lead off its plug without using too much force.
3. Pull the lead away from the plug one cylinder at a time, and ground the lead
against the cylinder head. This will prevent that cylinder from firing. The
engine will be running on only three cylinders as you test each cylinder
sequentially.
4. As you disable each cylinder, listen to the change in engine rpm and
performance.
If a cylinder is faulty, when it is disabled it will have little or no effect on
the engine’s speed or performance, as it will not be contributing fully to the
overall engine power.
A dwell-tachometer will give a more accurate indication of changes in engine rpm
as you conduct the test.
Ignition Wires
I would stick
with the stock type ignition wires as they often have a lower resistance than
silicone wires with graphite leads.
Rob reports -
My original set (of spark plug wires) stayed in the car 18 years till they
became hardened and brittle. (Dave, being obsessive and ultra-conservative,
replaced his after only two years.)
Dave wrote to John Connolly (Aircooled.Net) with regard to ignition wires to be
used with a CDI system -
I'm still not clear about the plug wires for use with the CDI system. Some say
the sturdier wires (i.e., Jacob's or Megavolt) are necessary; others say the
stock wires are just fine (mine are almost new -- I'm loath to replace them
already).
John responded -
If they are almost new, don't change them. However, give them a check once in a
while, because the additional spark energy can break them down quicker than with
the stock ignition (weak).
Spark Plugs
Someone on the
RAMVA Newsgroup wrote -
NGK's are the better of any commonly available
plugs, and can be cleaned with a wire brush, for so being re-gapped.
>
Dave wrote to Rob -
The Bug is starting to run rough. I think its those
cheap Champion plugs I put in (just because they were hanging around my work
bench) a few months ago. Tonight I'm going to let my fingers to the walking
through the Yellow Pages and try to find a set of the NGK plugs--B5HS for the
12mm ones, if memory serves.
Rob responded -
B5HS is the standard electrode plug. These are the
ones I'm using, and they are working well, but only 1000 miles or so on them, so
time will tell.
B5HY is the equivalent grooved electrode version, and I'll try to find a set of
these at next replacement time too, for comparison.
In NG parlance, B is the thread size 14m (A=18mm, C=10mm), 5 is the heat range
(2 is hottest, 13 is coldest), H is thread length 12 mm (# for 19mm), and S is
standard electrode (Y=grooved, V=precious metals, VX=platinum, etc) and you
might come across an additional letter for the plug gap (9 for .9mm, 10 for 1mm,
11 for 1.1mm, and 13 for 1.3mm; but not on the plugs suitable for VW as far as I
know.)
Rob wrote regarding grooved electrodes -
The multiple electrodes tend to shield the spark
from the mixture a little, which is OK in a slow revving aircraft engine, but
not so good in a higher revving auto engine. Then they developed a "surface
electrode" type, which had the cavity filled with bakelite or similar, and the
spark jumped from inward facing 'bumps' on the rim to the inner electrode, all
of which were flush with the bakelite filling the cavity. Supposed to be harder
to clog, because there was no cavity to hold the gunk. Not even used in cars to
my knowledge. NGK do make a grooved electrode plug though, and this is supposed
to make the spark on the outer edge of the side electrode, instead of jumping to
the center electrode right in the middle. Supposed to eliminate any possible
shielding of the spark more exposure to the fuel/air mix.
Rob wrote in response to a query -
The VW engine works best with Bosch WA8C or NGK
B5HS plugs. (Champion L87Ys are the right heat range too, but they have cut
threads not rolled and tend to strip out the aluminium heads.) You can do a plug
test by running down the road at a good speed (with the engine properly warmed
up), and shutting off/declutching/tuning engine off in the middle of the run,
and coasting to a stop. This is necessary so the reading is not contaminated by
any idling.
The plugs should have a grey/black thin coating on the rim of the threaded
section. The centre porcelain insulator should be off white, turning darker
deeper into the plug (about 1/2 way down the insulator) and the tips of the
outer electrodes should be grey/white, turning darker on the bend, to blend into
the dark grey of the rim of the plug. Black/oily is a good indicator of a worn
engine. Black/sooty means it's running too rich. Brown /whitish insulator and a
'white all over' outer electrode usually indicates lean running, often
accompanied by a light coloured rim on the plug. If the rim has a speckled
"pizza" appearance, the engine is detonating (even if you can't hear it), and
you try a different brand of fuel of go to the next higher octane fuel. And of
course if the centre electrode has rounded edges instead of a 'squared off' end,
and the outer electrodes are looking thin and burned, the plugs are past their
best and should be replaced.
If you can avoid using oxygenated (MTBE) fuels do so, your engine will run
smoother. Oxygenates result in less "fuel" in the fuel, and make old carburetted
cars like the beetle run lean, which means running hotter, and they don't like
running hotter since they are a hot running engine anyway. If you don't have a
choice, try switching brands, and DO use a "pump octane" of at least 87 maybe
higher if it needs it to avoid detonation.
Rob responded to another query -
Just to check, are your old plugs the 1/2 thread,
or the longer 3/4 inch thread? If your car has the newer style replacement heads
(they are interchangeable), they will need the 3/4" plugs B5ES ("E" for
"extended" thread).
With the engine out, it might be possible to shine a torch down a plug hole and
check. If the heads are the newer 3/4 inch type, and you have 1/2 inch plugs in
them, you'd see a blackened section of unused thread at the bottom of the hole.
The short plugs will fire in the newer heads, but less efficiently, as they will
be "buried" inside the heads.
Dave asked of John Connolly (Aircooled.Net) -
I'm running NGK plugs that are less than six months and 1000 miles old -- can I
clean them up, gap them to 0.040", and reuse them (with a CDI system)?
John's short response -
Yes.
Spark Plugs in CDI Systems
Rob wrote in
response to a query regarding spark plugs in CDI systems -
The regular plugs should be OK. B5HS is right.
Widen the gap a little from the normal, and there is a possibility that the
STANDARD plug leads will occasionally arch, since they are running at 38,000
volts in lieu of the normal 20,000.
As a start, make sure the distributor cap is clean and dust free, but before you
clean it, have a look at it at night with the engine running. It's a common
arching point (between the rubber caps) - you can see any arching at night.
If it's arching there, it may just need the thicker (insulated) leads, and an
occasional wipe of the distributor cap.
Dave asked -
I wonder if I don't need to be running hotter
plugs, since the CDI system almost doubles the voltage across them.
Rob responded -
The plug "heat" is actually a function of the
cylinder head temp more than anything. A "hot" plug retains heat in the centre
electrode longer than a "cold" plug. A hot plug has a long centre electrode -
the join to the shell of the plug it deep inside the plug. VWs need a coldish
plug to counter the fact that they are shedding heat into a hotter than normal
head. So is the NGK B5HS a "coldish" plug.
Dave's question continued -
The bottom line on the spark plugs, then, is NGK
B5HS with a .040" gap. Just wanted to make sure that you concur.
Rob responded -
Yes. But as I said, if the misfire continues,
suspect the leads and a dirty (doesn't have to be much) cap first. Oh - and
clean the inside of the cap too, if it doesn't look shiny clean.
Rob wrote -
There is a possibility that the STANDARD plug leads
will occasionally arc.
They are sometimes described as high tension plug leads, or 8mm plug leads
(thicker insulation) - but I don't know what they'd call them in the US.
You had new standard leads I remember, and these SHOULD be OK, so hopefully a
good clean around the cap and maybe the leads too might be enough.
Miscellaneous Questions and Answers
All responses are from Rob Boardman unless otherwise
indicated.
Question -
When I couldn't start the car the other day, I had
to leave the car at the wash. I disconnected the spark plug wires to deter
thieves. When I got there the next morning I put them on the wrong cylinders!
So, I pushed the car 1/2 miles to my house over mixed up wires!
Response -
I'm not laughing -- it's easy enough to do, and a
hell of a good lesson in the school of hard knocks.
One trick I found useful for this was to put a twist of copper wire around the
spark plug leads near the plug ends. One turn for No1 cylinder, twice around for
No2 and so on. Can't mix them up then unless you remove the wires from the
distributor too.
Question -
I own a 1968 model beetle which is a 12V one. I
would like to enquire regarding its spark plugs and hope that you don't mind.
In one of your articles, I noted that you mentioned NGK plugs B5HS. Here in my
home town, I can't get them but the dealer told me to use B6SS. Is it OK and
what does the figures on the plugs indicates such as 5 or 6. My plugs also
appears to be black/oily and what does it indicates.
Response -
I have the NGK Spark Plug Guide in front of me...
The NGK letters and numbers mean -
B - 14mm plug (A-18mm, C-10mm etc)
5 - heat range - 2 is very hot, 13 is very cold.
H - thread length 12.7mm (E for 19mm)
S - "standard" electrode type (Y for grooved, P for platinum etc)
The 6 heat rating should be OK - it's just a fraction "colder" than the 5, and
should be OK in your hotter climate. "Colder" for a spark plug means that it
gets rid of heat faster than a "hot" plug.
But you said B6SS - the character after the number should only be an H or E
indicating the length of the threads. There is no S length - only H and E. If
you really meant B6HS, then yes - that should be fine.
Black and oily usually means that the engine is starting to burn a little oil
(starting to get worn). If you use a colder plug (the B6HS) there is a
possibility that they will oil up more, but there's no way of telling untill you
try them and see if they oil up too fast and stop working.
If the deposits were black-sooty I would say that it's just running a little
rich, but black-oily usually means it's burning a little oil, so you might keep
a check on the oil level too, just to make sure it's not using too much between
oil changes.
Rob commented -
I changed the spark plugs on the weekend.
The old ones are Bosch W8AC and all were in quite good condition for 12000+
miles. Nice to see that all plugs looked the same - all cylinders performing
about the same.
I might take a close up photo as an example of the correct heat range (clean
ceramic centre post, black rim and colour change from grey to black on the outer
electrode, right on the bend.)
It will be interesting to see if the NKGs (replacements) look any different
after they have done the same miles.
Question -
After I had picked up the vehicle I noticed it
pinging under acceleration… (Mechanic) sent me on my way stating that if I was
not happy to bring it back to him again and he will try a different set of spark
plugs.
Response -
Changing spark plugs will not cure
pinging/detonation. Only timing and choice of fuel would have any effect there,
since we are not talking about altering the compression ratio (the only other
consideration in eliminating detonation).
You can get a lot of other useful information about type2 VWs at
www.vitangebus.com and
www.type2.com.
Our friend Leo in Venezuela wrote -
So now I'm in a new little project on my car.....
he spit away a spark plug, so I had the thread fixed an made the job on three
sparks.
The fact is that the fourth one had already this job done, and spit last week
the spark plug again but with the copper threaded insert, so I think it was a
rebuilt head....
Response -
That's unfortunate, but it can happen with old
heads - the thread is only aluminium so rough handling in the past could have
damaged the threads. I always use Bosch or NGK spark plugs because of this -
they have smooth threads. Some other brands have sharp threads which damage the
heads more easily.
Capacitive Discharge Ignition (CDI)
Material gleaned from various VW newsgroup conversations and direct e-mail
correspondence.
A conventional induction ignition creates a spark by applying electric potential
(12 volts) to the primary side of the coil. The coil steps the primary potential
up to as much as 10,000 volts and delivers this high voltage to the spark plugs.
However, this "step up" process is relatively slow, and as crank speed (rpm)
increases, the secondary voltage declines dramatically.
This limitation was partially solved by the development of capacitive-discharge
ignition (CDI) systems. Instead of applying 12 volts to the coil, a CD ignition
increases the primary current by storing it in a kind of miniature battery
called a capacitor. When this higher primary current is applied to the coil, the
secondary voltage is dramatically increased.
The principal advantage of a CDI system is the ability to present a superior
spark to the air/fuel mixture inside the combustion chamber, thus maximizing
burn efficiency. The easiest way to get a bigger spark is to increase the spark
plug gap size. However, increasing the gap distance also increases the voltage
necessary to ionize the air/fuel mixture. And the resistance of the air/fuel
mixture increases as the mixture is pressurized in the cylinder, requiring even
higher voltage to spark across a plug. A CDI system provides the higher voltage
required by the increased spark plug gap size, thus providing very intense
spark.
A CDI ignition system can create spark potential as high as 37,000 volts. Most
engines only need about 20,000 volts for reliable ignition. The stock system
begins to 'droop' as the rpm goes up. At highway speeds, the spark voltage
becomes more and more marginal, averaging about 18,000 volts. With a CDI system,
the step up process is very fast compared to a conventional 12-volt induction.
This assures a more consistent spark delivery across the plug gap, even at very
high crank speeds (rpm).
A note
-- the consistently higher voltage will cause neoprene-type insulation to break
down rather rapidly. You need sparkplug wires with better insulation, such as
silicone or non-metallic.
The carbon conductor in the non-metallic leads will produce less radio
interference and won't corrode like metallic leads. Electrically, if you've got
37000 volts available, the ignition system can't tell the difference between
metallic & non-metallic leads.
We recommend NGK spark plugs, gapped to 0.040 inch. (See our tune-up procedures
for more detail regarding spark plug removal and reinstallation.
A note from Bob Hoover
-- The CDI module doesn't claim to be anything special, just a good basic
ignition system. If all you want is a good, reliable ride, it's the best idea
since beer in cans. It will save you money, help clean up the environment and
make your car run better, all at the same time.
Rob wrote regarding the CDI system -
The CDI ignition kit DOES help with
cold starts and fractionally better economy. The plugs DO last longer too. The
one I built many years ago worked well with the standard plug wires, but I
suppose the more modern ones would need better wires for the higher voltages
they generate.
Question -
Isn't the points triggered CDI
different than the electronic points replacement CDI? I know they sell two
different ones. Just trying to save someone from having to buy two. But, I could
be wrong, sure wouldn't be the first time.
Bob Hoover responded -
Two types of CDI units are offered
-- a points-triggered CDI module and an optically-triggered CDI module.
VW distributors are not well sealed. There is always some amount of oil vapor
inside the unit. Combined with the carbon granules that wear off the central
button in the distributor cap, over time this obscures the IR pickup on the
optical sensor and results in misfires. It doesn't happen suddenly you get some
warning that things aren't working right and a Q tip soaked in alcohol cleans it
right up... but there's plenty of times, such as when you're in freeway traffic,
when you just can't afford to have your engine start missing.
The points triggered module is designed to trigger off the stock points and
works equally well when triggered by an electronic switch that uses magnetic
sensing, such as the Pertronix.
The basic circuit in the CDI module -- the 'singing aluminum brick' you mount on
your firewall or wherever, stays the same no matter what method of triggering is
used. The two modules (points-triggered and optically-triggered) are not
interchangeable without going inside the unit and resoldering some wires.
The stock points work okay for triggering the unit... sorta : ) The points never
wear out since the triggering signal is only about two hundred and fifty
milliamps (a quarter of an amp) as compared to 10 or 11 amps in the stock
system. But the rubbing block wears down and you have to regap the points every
25000 miles or so. And as the miles build up the spring on the points weakens
and you start to see points bounce, even at fairly low speeds. But points are
inexpensive, robust and universally available making their use practical. I
started using CDI modules in the 1960's and used the stock points for triggering
until something better came along.
As a final note, a lotta guys go to a CDI module because they are having
ignition problems and sure enough, the problem goes away once the unit is
installed. You'll hear this same story from guys who merely replace their points
with a Pertronix or other brand of electronic switch. But the odds are, the
problem would have gone away with a good tune-up or rebuilding the distributor,
which needs its seals replaced about every 50000 to 70000 miles. If your
distributor needs an overhaul, the mainshaft will be loose and that looseness
will cause excessive 'hunting' -- the spark won't always occur at the proper
time.
A CDI module will trigger reliably with a point gap that's too small to measure
(!), meaning it will even trigger reliably (although not accurately) with a
distributor that is virtually worn out. By the same token, replacing the points
with some form of magnetic triggering often masks that wear. Your distributor is
still worn out and should be overhauled or replaced but the 'hunting' will have
vanished... right up until the mainshaft binds or the dog gear breaks off or
some other catastropic failure occurs.
There's no such thing as a free lunch : )
CDI Installation
Question -
Soon our Bug is going to have a silver finned box
mounted on the fan housing to boost the voltage in the ignition system. The
instructions say to mount it as close to the coil as possible -- is it OK to
drill a couple of holes in the fan housing and mount it with the sheet metal
screws that are provided?)
Rob responded -
You could put it on the fan shroud -- it wouldn't
worry the shroud at all, but that means it will be subject to engine vibration.
Another good place is on the left side of the firewall, near where the wiring
harness comes into the engine bay. This has two advantages, it gets less
vibration, and it's in the path of cooling air being sucked into the fan through
the grills above. You just need self tapping screws long enough to penetrate the
firewall padding, but not so long they poke through the carpet/felt on the
inside.
That means the finning will get some useful airflow over them. It DOES run hot
it's the nature of the beast. That's what finally killed mine off several of the
components slowly cooked themselves, and it wasn't worth fixing it up. My
version had a plain box (no fins) with the power transistors mounted to the box
itself. They were OK, but several components inside the box cooked. Hopefully
the improved layout of commercial units like yours, with the finned box, will
stand up better. Had I known I might have tried putting air holes in the side of
the box.
CDI Installation Procedure
1. Locate a location for the CDI unit as close to the coil as possible (e.g.,
firewall. The fan housing may not be a good location because of vibration).
NOTE: The firewall is ribbed for strength, so you might find some screws go in
further than the others before touching the firewall.
2. Mount the CDI unit with metal screws supplied in the kit. Use toothed lock
washers under the screw heads to assure a ground connection. Alternately, run a
14 gauge wire from one of the CDI mount screws to a body bolt.
3. Disconnect all wires from the negative (-) side of the coil.
4. Remove connectors from the wires removed from the negative side of the coil.
Twist all of these wires together and attach them to a female terminal
connector.
5. Connect the black wire on the CDI to the negative terminal on the coil.
6. Connect the green wire on the CDI to the green distributor wire.
7. Remove all wires from the positive (+) side of the coil.
8. Removed connectors from the wires removed from the positive side of the coil.
Twist all of these wires together and attach them to a female terminal
connector.
9. Connect the CDI white wire to the positive side of the coil.
10. Slip vinyl tubing from the kit onto the CDI red wire. Connect the red wire
to the ignition wire removed from the positive side of the coil. Move the vinyl
tubing to cover the terminal.
CDI Wiring
Wire |
Connections |
Red |
Ignition switch, automatic choke, electro cutoff valve, backup lights
|
Green |
Green wire from the distributor |
Black |
Negative coil terminal (#1) |
White |
Positive coil terminal (#15) |
Electronic Ignition
Material gleaned from
various VW newsgroup conversations and direct e-mail correspondence.
Advice from John Connolly (Aircooled.Net) -
Replace your points and condenser
with electronic ignition (e.g., Pertronix or Compufire) Takes only 20 minutes to
install. Contrary to popular "wisdom", you are not going to get a huge power
increase with this part. You WILL get a no-maintenance item (unless you love
adjusting points and timing), which gives rock-steady ignition timing under all
conditions. In my opinion, this is a must-do modification even for stock cars!
Getting the rubber grommet into the hole properly is the hardest part of the job
(I'm not kidding).
The Wisdom Bob Hoover regarding
Electronic Ignition -
If you want to make it last forever,
or at least longer than the 70,000 or so it normally lasts, get rid of the
points. Opening the points represents as asymmetric load on the distributor.
Opening the points is the major cause for wear on the shaft and bushings. So get
rid of them. Use a Pertronix unit. No load on the distributor shaft. Runs
concentrically. Vastly reduces the wear-rate which is already pretty low because
the distributor only turns at one-half engine speed. (Don't use an optically
triggered unit. The Pertronix is magnetic.)
Buy a Pertronix 'Ignitor' that fits your distributor. Pull the distributor and
install the 'Ignitor'. Be careful of the wiring. One lead is +12v, the other is
the signal lead... it goes to the coil's negative terminal. The ground is
internal through the body of the distributor.
Be sure to set the proper air gap and make sure the Hall effect sensor (the
black epoxy cube on the aluminum plate) is standing square to the plate. I've
installed several of these and most were bent right out of the box due to
improper riveting. Easy enough to straighten but if you don't notice it the
thing can actually rub against the magnet ring... not a good idea. (And yes,
it's 'magnet' not 'magnetic'. There are four high-strength magnets cast into the
nylon (?) ring that fits down over the cam lobes of the distributor shaft.)
Make sure the magnet ring is pressed FULLY down onto the cam lobes. There are
instructions with the Ignitor but the illustrations don't look much like the
real thing.
Put the rotor back on. (You can expect to wear out a rotor about every two years
due to the higher spark voltage. Just carry a spare so it won't leave you
stranded. Ditto for the cap.) Make sure the ROTOR seats fully. On some
distributors, you can't use the 'Ignitor' because the magnet ring prevents the
rotor from seating full depth. (But you can machine a bit off the lower edge of
the rotor, if you're careful doing it.)
Fire it up. Hey! Now THAT's a difference. Reason is,you've just eliminated a lot
of mechanical jitter that is present in most old distributors. The jitter is
still there but the triggering method used by the 'Ignitor' masks it. No more
points bounce. In fact, no more points, period. Your plugs are now being fired
in response to an electronic signal that is far, far more precise than any
mechanical switching arrangement.
Slap a strobe on that puppy. And plug a sniffer up the tail pipe -- you can lean
that thing down by quite a bit, now that you've got a higher spark voltage.
Static timing okay? Then go ahead and kick it up to where the advance is all in
and check the max. Dial it back down to thirty degrees or less. (I run 28. Yeah,
I know. But I'm more concerned with getting there than how fast I can get
there.) Hot weather, bad gas, heavy load, crank it back a bit more. And tweak
your idle down better ignition has caused your idle rpm to increase. Keep them
between 800 and 900 rpm. Any slower and the engine won't cool properly when you
come off the freeway, etc.
Now here's what's gonna happen. Your mileage is going to take a nice jump. Most
folks report an improvement of 8 to 15 percent. Depending on how much you drive,
that alone will pay for the mods in about two years. But the driving! Damn! The
thing really DOES run better! That's because you've gotten rid of points-bounce
and shaft-jitter and incomplete combustion at higher rpms. And that means your
engine will last a little longer because your oil is going to stay a little
cleaner because there won't be so many unburned hydrocarbons in the blow-by that
gets into the crankcase.
Plus it's going to start better. A LOT better. And no more cross firing during
damp weather. And your engine is running cooler, too! Those Corvair-type air
seals really make a difference.
I've been using such an ignition system for nearly thirty years -- it's been
available that long. I first wrote about it on the internet more than five years
ago... and immediately got a blizzard of flamers and hate mail -- lots of
kiddies shouting 'If it's really that good and really that easy, then why
haven't we seen anything about it in the magazines?'
Question -
Today a friend suggested installing
electronic ignition. Have you had any experience with this? Might it be a good
thing to do?
Jim Mais ("Speedy Jim") responded -
Electronic ignition is nice ... but
... it's not a panacea. The stock ignition should make that engine run just
fine. First find out why it doesn't run right.
Question -
I was wondering what models people
had luck with. I stray away from Pertronix because they have had so many
warranty claims.
Response -
I've had great luck with the
Pertronix. I think the warranty claims were mostly because the unit was a bit
too big for the 009 distributors, and didn't fit right. It wasn't possible to
create a gap, it rubbed. They've fixed that, and now it fits fine. The unit
itself works fine. I have one in my '70 Ghia, and I've driven it for 6 months
that way, with zero problems. I also talked to a lot of people before buying it,
particularly shops that sold both units (Compufire and Pertronix). The unanimous
opinion was Pertronix.
Question -
Pertronix is a primary improvement,
and only removes tuning up the points/condenser. The other performance is the
same.
Bob Hoover responded -
The above isn't entirely true. The
points represent an asymmetric load on the distributor shaft. With mechanical
points that asymmetry leads to some degree of "hunting" at low speeds.
At higher speeds the inertia of the system tends to damp-out the hunting, but,
depending on the age of your points and the amount of wear in the system, you
begin to experience some degree of points-bounce.
The Pertronix units I've bought and tested eliminated both of these problems.
The net effect is a more stable, more uniform ignition at all engine speeds and
some small improvement in fuel economy because of it.
Question -
The next investment that I'm
considering is a Pertronix system. I hear Bob Hoover and others talking about
how this will save you from having to fuss with the points, but is there a clear
advantage performance-wise?
Response -
Nope. The hotter spark of the CDI
gives you better performance, but the Pertronix simply replaces the points with
an electronic trigger for the CDI. So it will stay timed longer need almost no
adjustment, as it has no rubbing/wearing parts.
The only performance advantage would be staying in tune. I guess that if the
engine was running at high revs a lot you'd also have the advantage of no
"points float" which tends to upset the timing a little, but since you car is
not a racer I doubt you'd notice ANY difference in performance. I'm certainly
not knocking them, I'd be quite happy to try it out just don't see the need if
you are happy to check the timing regularly.
Question -
While my car runs very well I would
prefer it was stock. Do you have any experience or knowledge about this subject
and also do you have any experience with the Petronix Ignitor pointless system?
Response -
Petronix - I haven't used one my
self, but I know how they work. You replace the points with the sensor (and you
usually need a new resistor-less rotor arm too) and the sensor provides the
trigger for the normal coil. So you get normal spark voltages, but no wearing of
points and usually less "shake" in the timing, since it's only distributor
driveshaft wear which could now cause "shake" and not the points cam and jumping
points too. Since there are no points to wear, the timing doesn't alter and you
have less tuning to do.
Ignition Questions and Answers
Dave confessed to a mistake -
I accidentally attached the wire from the ignition
switch to the wrong side of the coil.
Rob offered the following advice -
Probably blown the condenser. My guess is the coil
will have survived. If you have a multimeter, you can test the primary 12 volt
circuit (the and + connections). Zero resistance means it's blown any resistance
means the circuit is still intact. the secondary (high voltage) circuit will be
OK it's unlikely to be affected by a blown primary circuit, so you won't need to
check this (if you want to, you check between the centre electrode and earth and
you'll need to use a high resistance scale I forget the range it should be in,
but much higher than the primary.
Also have a look at the little (should be black) wire on the points this might
have melted. Also check the fuses quite possibly blown one of these too.
Also check the wiring to the idle cut off and choke -- cross wiring might have
cooked these.
Condenser, the points wire in the dizzy, and the fuse are the most likely
damaged parts.
One easy check (so you don't "shock" yourself with the main coil wire), is to
use a spare plug on any of the plug leads and rest the plug on some exposed
metal, such as against the inlet manifold near the plug holes. You should get a
spark, and it's easy to see if it's in the shadow down there.
John Connolly (Aircooled.Net)offered the following advice -
Replace the ignition cap and rotor: three minutes (give or take). Bosch is the
ONLY brand of these parts that I recommend you install. Leave the clear
distributor caps for the show cars (they run like crap). Make sure you switch
wires one at a time!!
Question -
I am searching for an answer to my ignition
problem. I have power going to my coil but it is not making it to the plugs. I
have replaced the rotor, points and condenser. Is their any other checks I can
do on the condenser or something else?
Response -
Disconnect one side of the coil (either one) and
put an ohm meter across the primary terminal ( + and -). You should get 3-4
ohms. If it's either high or no resistance, the primary coil is shot and you'll
get no sparks from that coil.
If the resistance is OK, then he could try wiring a spare plug to the centre
wire, resting it on the case and turning the ignition. Should get a nice stream
of sparks at the plug (all four cylinders worth). If not, then the problem is in
the secondary (high voltage) winding of the coil. Replacement coil should fix
either of these problems.
Question -
I read in a Clymer Manual that I could have shorted
out my distributor, does that mean the points and condenser? I assume so -- I
don't really know. The term "shorted out" would obviously refer to the
electrical components -- I'll bet they're talking about the cap.
Response -
The only way of "shorting the distributor" is to
put the wires incorrectly on the coil - reversing the + and - connections so the
current is flowing the wrong way through the points. This can blow the
condenser, and may cause pitting or burning of the points (obvious to look at).
Question -
I have an old distributor with the single vacuum
line and one wire coming out from the condenser. I didn't want to change it out
for a newer one.
Dave's impetuous response -
Absolutely not! This is a Single Vacuum Dual
Advance (SVDA) distributor, the best match for the 30 and 34 PICT carburetors.
Don't let someone try to talk you into a 009 centrifugal advance distributor!
Rob's calmer voice -
You may be talking about some later VW distributors
with a different condenser arrangement. Some use the canister as one side of the
circuit - so it's firmly attached to the distributor body. Some use a "two wire"
condenser and that has to have one wire attached to the condenser and the other
to the coil (as normal). Electrically, either will work.
Tune-up Procedures
Written for Dave's 1973 VW Super Beetle,
but will apply to any aircooled Volkswagen
~~~
Step 1. Compression Test
1. Start the engine and warm it up for about 10
minutes.
2. Pull the spark plug connectors off all four plugs (careful--the engine is
hot!)
3. Inspect the wires and the rubber seals on the ends. If worn or defective,
replace them.
4. Stow the wires so you'll know what goes where.
Note: A handy trick is to wrap thin strands of copper wire around both ends of
the spark plug wires--one loop for Cylinder #1, two loops for Cylinder #2, and
so on. This way there is no question about which wire goes where. Refer to the
diagram at the beginning of the Valve Adjustment procedure to see which cylinder
is which and where the firing point for each is on the distributor.
5. With the spark plug socket on the ratchet, loosen all four plugs until
they're hand tight. Use the extension and socket to screw out the last few
threads by hand.
6. Lay the spark plugs out in a pattern to match the way they came out of the
engine. You will carefully inspect and gap the plugs in the next step.
7. Check the compression with the compression tester:
o Hold the rubber end of the tester in the spark plug hole, tightly.
o Have a buddy turn the engine over six times and record the data.
o The test results should be over 100 pounds and within about five pounds of
each other.
o Low readings indicate need for an engine overhaul.
8. Since you have the spark plugs out, proceed to Step #2, "Inspect, Adjust and
Install Spark Plugs."
Step 2. Inspect, Adjust and
Install Spark Plugs
1. Pull the spark plug connectors off all four
spark plugs.
2. Inspect the wires and the rubber seals on the ends. If worn or defective,
replace them. The large rubber seals around the spark plug leads are important -
they seal the cooling air in around the heads, and MUST be replaced if they
won't stay snuggly against the hole in the tinware.
3. Stow the wires so you'll know what goes where.
Note: A handy trick is to wrap thin strands of copper wire around both ends of
the spark plug wires--one loop for Cylinder #1, two loops for Cylinder #2, and
so on. This way there is no question about which wire goes where. Refer to the
diagram at the beginning of the Valve Adjustment procedure to see which cylinder
is which and where the firing point for each is on the distributor.
4. With the spark plug socket on the 3/8" drive ratchet, loosen all four plugs
until they're hand tight. Use the extension and socket to screw out the last few
threads by hand.
NOTE: It's best to wait until the engine is cold before removing the spark
plugs. If you try to remove them from a hot engine, you run the risk of galling
the threads. Bob Hoover has strong feelings about this -- "This is the standard
rule for aluminum heads, and has been since the 1920's. The world is filled with
engines having aluminum heads, but about the only folks who seem to have trouble
with stripped spark plug holes are kids with Volkswagens. I wonder why that
is..."
5. Lay the spark plugs out in a pattern to match the way they came out of the
engine.
6. If you are going to reuse the plugs,
inspect them carefully, comparing them to the pictures in the Bentley manual. If
necessary, clean the plugs or install new ones.
7. Set the gap between the bottom bent electrode and the center straight
electrode to 0.028" using the feeler gauge on the gapping tool. The bent
electrode can be carefully bent in and out with the gapping tool to make the
adjustment.
NOTE: If you have a capacitive discharge ignition (CDI) system installed in your
car, the spark plugs should be gapped to 0.040".
8. Make sure there is a gasket on each plug, then put the plug in the spark plug
socket.
NOTE: If the plug is very tight in the socket, you will have a very difficult
time getting the socket off of the plug once the plug is installed. To prevent
lots of frustration, apply some silicone grease to the plug before putting it in
the socket; this will make removal of the socket much easier. Be sure to wipe
the grease off the end of the plug before installing the spark plug wire.
9. Put the plug in the cylinder that it came from and hand tighten with the
extension (do all four). Put on the ratchet and tighten them all--fairly tight
but don't overdo it (snug and a tug). The cylinder heads are soft aluminum, so
be careful you don't cross thread the plugs - they should start in the holes and
turn fairly easily just using your hand. Torque the plugs to 22 ft-lb with the
engine no more than warm.
A very pertinent note from our friend Bob Hoover: "Be damn sure to use a dab of
anti-sieze on the threads of the plugs and that the compression washer is in
place. Install the plugs BY HAND until the thread is full depth. Don't put a
wrench on the plugs until they are fully threaded into their bores. And if you
can't thread them in by hand, you've got galled threads and need to do something
about it -- it ain't gonna heal itself."
10. Put the plug wires on the same way you took them off. Make sure the rubber
seals are pushed down firmly on the spark plugs and that the rubber seal is
seated properly in the hole in the tin.
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