Adios Guadalajara… Almost
The next day, another mechanic friend comes over to check over the bus. He drives a killer “rat look” splittie and it’s completely full of tools.
The alternator is now the top priority on our list and it immediately gets pulled out. Brushes are good, so the internal regulator is the diagnosis. They hop into their car and run to get another one and return and put it all back together. Still no good. Regulator is still the diagnosis. They hop back in to the car and go get another one. After putting in the second one, it seems to be fixed. This takes most of the day, but we’re still missing on #1.
At idle, you can pull the #1 plug wire and nothing happens. It seems to work at higher rpm. We replace the wires and plugs… again… and still no change. You can pull the plug wire off the cap about 1/4” and it seems to start firing at idle. Plug it back in and nothing (this is why the other guy suggested increasing plug gap and tightening the valve.) It seems to be electrical and we decide to drive it a bit and fully charge up the battery with the rebuilt alternator and see if it’s related. I can’t help but think it might also be the carb, but since #1 and #2 share an intake and #2 is fine I’m not sure how to explain it (same for #3 and #4.) Juan knows a carb guy, but he’s not available for a few days. The mechanic jokes that after 180 km the problem will go away. Good enough for now. We tweak the carbs again and call it good enough to continue moving on.
Symptom: seems to be misfiring on #1 (less on #3) at low RPM. You can put an inductive tach on the #1 and #3 wire and it seems to be missing (bad readings, intermittent strobe). #1 and #3 plugs get black and carbonized. #2 and #4 are tan/gray and look fine. We’ve got a 009 dizzy (timed at 30 deg full advance and 7 deg at idle) and Dual Kadron carbs.
The problem seems to mainly be when the engine is cold and idling
Compression is 110 psi on all four cylinders.
All valves are at 0.006”
New coil, cap, rotor, wires, plugs
Different cap and rotor and 009 distributor have been tried with no change.
Both points and electronic ignition have been tried with no change.
New plugs and wires have been tried many times.
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not sure this will help but I alway run a ground wire from the nut on the generator/alternator stand to the place where the battery is grounded on the chassis. I do this with all my vw’s and seems to work fine. just a thought. good luck!
What kind of advance/retard do you have on the dizzy? I don’t know about the earlier engines, but my 1800cc FI engine has a dual vacuum advance that is pretty complex with all the vacuum hoses running everywhere. Maybe the problem lies with a similar mechanism.
Switch the #1 and #2 wires in the cap and on the plugs and see if the problem jumps or stays. If it stays the contact of the cap might be wrong. Is the cap the right one for a 009? Not the same as vac adv dists. Check the rotor height by pulling both clips back and gently setting the cap on the dist- it should sit above a tiny bit but push down and then compress the spring. Also check that the rotor is wide enough to reach the contacts inside- too much gap means wrong part. Are your carbs on manifolds that are isolated front and back? In other words no plenum or one path for both cylanders. Check the balance tube between carbs for leaks and the base gasgets- spray some WD40 or water at the sealing areas while running and see if the idle raises(WD) or drops(H2O).
#1 missing when cold and idling? How about when it’s warmed-up and idling? If so, sounds like weak spark. If you’re running a pertronix, I would look for the rotor and cap. Bosch? Qaulity parts for ACVW are getting harder and harder to get. This adds a lot of confusiion while trouble shooting because we all want to use the process-of-elimination method by using a new part with the assumption that it’s “good”. And this very well may not be the case.
hey jason Take the valve cover off and spread something below it to catch the oil that will come out. have somebody start the engine and spray carb cleaner around the valve springs on that clylinder. If it picks up RPMs then your valve guide is either worn or loose later md
Very possibly you have an intake manifold/port leak at cylinder #1. This lean condition causes a misfire at idle but cleans up at higher rpm. You can adjust the carbs and be satisfied with synchronization between banks and still have this issue. Plug color would tip you off. Check for leak with cool engine and a spritz of WD-40, if idle changes, you have a leak. It is not just the gasket. Aftermarket manifolds are famous for warping.
It should be noted that if you have a balance pipe between the front pair (otherwise known as a brake booster circuit) you can also have a lean condition shared by #3 and #1 because intake strokes are scavenging balance pipe air instead of drawing in fresh mixture.
Colin
I checked all this already, but you’ve convinced me to give it another try. I’m tempted to completely remove the vacuum (it’s only used for the brake booster) and drive around without it. I might have to wait until we’re out of the mountains, though!
I also have no real way of guaranteeing I have the ‘correct’ cap and rotor. Any tell-tale markings?
For the misfire on #1 I would suspect that there is a intake manifold gasket leak at the cylinder head. To check this, run the engine and then spray some Brake Clean at the intake manifold area. If the engine RPM increases that means that it is sucking in the Brake Clean and using it as fuel to off set the lean mixture. The reason that it runs better when the spark plug wire is pulled up 1/4 inch from the cap is that it increases the spark KV going to the plug. A lean running cylinder needs more KV to fire then a proper runnig cylinder. Also, check the intake boot that is between the intake manifold and the carb manifold. Leaks happen there all of the time. And last on the subject, check and make sure that the crosover pipe (Pipe that runs along the intake manifold to the exhaust pipes at #4 and #2) is getting warm. If it is blocked if will effect fuel atamzation and cause fuel to puddle up in the intake.
For the Charging System, tey doing a Voltage Drop test on the Ground Strap, Positive Cable to the starter, and the Positive Wire to the Alternator. To do a Voltage Drop test, take you Volt Meter and run it parrall with the wire you are testing. For example, for the ground cable, you would put the black test lead onto the negitive terminal of the battery and put the red test lead onto the engine case. Turn the meter to read volts. Crank the engine over and whatever volts you read on the meter is how many volts you are lossing through that wire. Anything over .2 volts is bad.
Good Luck. Brooks told me to give some tech advice. I hope it helps.
Todd Crum