My faithful Beetle has stumped the local mechanic! He has never been so flumoxed with a car before.
It is a 1976 Beetle, 1600 engine, single empi hpmx carb, pertronix ignition module.
It suddenly started missing a couple of weeks ago. really bad under load. It is only missing on the 2 cylinders on the passenger side.
Today the mechanic showed me something interesting. With the engine running, he pulled off a spark plug lead and held it close enough to the dizzy for the spark to jump across. Seemed to be running fine. Attached the lead properly again, started misfiring. Seems to be flooding on that side too.
Any ideas? At all?
Thanks.

just change the spark plugs check for a crack in dissy cap and then the timing.
easy fix.

also the rotor button

Talked to the mechanic again. He has already trid all the above. Made no difference.
Could it be the pertronix setup? The dizzy did get water in it not long before the problems started.

Try a cheap 009 and see if it is any different

Umm, yeah - electronic ignitions don't like getting wet. Pertronix, compufire etc. all basically the same... they LOOK waterproof but generally aren't.

I'd say throw a set of points at it and see what you get.

Put a new set of leads on it. Check manifold boot is not split on that side.

Also check the idle jet for that side, could be partially blocked, and check the idle mixtures

We have tried replacing the rubber manifold boots, plugs, leads, dizzy cap and rotor. No difference. Carby has been cleaned and cleaned again. Just waiting on getting another 009 dizzy to try.

Could it have anything to do with sticky valves? or any part of the head on that side?

so I am assuming that you did check the compression??
and you did change the spark plugs while you had them out??

this happened to me many years ago and my father cut the ead striped the rubber back on both ends and threaded one end through 2 holes and theother end through the other 2 holes and my old riley went great i asked what happened he said the cylender was either losing compression and oiling up the plug or the lead was rooted i didn't care the car ran
what you said about the lead jumping reminded me .so what does that say about your car eather vales are tight or a new wire would not hurt it will be something todo with the sparkegoodluck

So... the pertronix module that got wet has been in there the whole time... you haven't tried points yet ???

Just have to wait till I get another dizzy.
A friend of mine also said it could possibly be a bent pushrod?
We will wait and see. I'll let you know the result next week.

Thanks for your helpful input so far.

I'dd be checking the head to manifold seal again as these can be stuffed up quite easily ( even twice ) , to check if this joint is leaking , carefully spray some water around the area while idling and if the motor picks up revs a bit and or runs better then bingo youv've got it

tight rocker

Ok. Finally back.
Tried brand new dizzy. No luck.
Mechanic has just removed engine and has has thoroughly checked the valves, pushrods etc. All very good.

So now we go back to the beginning.
He said it seems to be flooding on that one side. When he pulled engine out, lots of fuel sitting there. So must be back to carby.
It is a single Empi HPMX, so it does feed one side from each barrel.

Have you heard of this problem at all?

so the compression was good??

I have had that same thing , when you pull the plug lead away the engine ran better and it was just crooook spark plugs.

you have something funny going on there.

Mechanic has finally brought car back. He has given up on it. Now it runs worse than ever. We had to tow it home!
Bought replacement carb. back to 34 Pict 3. I have had it running just this afternoon. Nice.
Or so I thought. Took it for a quick test run. As soon as it hits a slight hill it just stops. No power at all!
Stop and it idles nicely again.

Any ideas?

did u take it to a volkswagen mechanic?

if your motor isnt just plain worn out from being over heated or worn cam shaft or something , try and advance the timing up to about 15deg and go for a road test and see what happens , see if motor pings , if it goes better and don't ping you may just try setting timing by ear.

How bout this for an out there theory? could the exhaust be partially blocked somewhere? Everything else has either been checked or replaced.

I'm liking the VW MECHANIC idea. Where are you ?

I am in Hobart. Only about 2 specialist vw mechanics. the mechanic i was using has been talking to one of them about the problem. His immediate suggestion? Pull the engine apart and rebuild it! What!
Doesn't sound like a good solution to me.

But?

do it by the numbers new plugs 2 carby kit 3 compreson test 4 tappets right setting 5 replace points AND condensor 6 do timing 7 recheck fuel line from tank to carby 8 burn the bugger and have a bbq

maybe you have checked it but is the timing advancing with RPM.

so did the bloke really try new spark plugs , really?????
then test drive ?????
did you pay for new plugs on your invoice.???
as it often the simple things.

A mate of mine and I worked on it again yesterday.
Mechanic said he had tried new plugs, new leads, new coil, new dizzy. But maybe not all at once?

We had the poor old bug idling away nicely on only 2 cylinders! No. 2 and 4 plugs were dead! Plus coil seems to be not quite right too. And coil to dizzy lead was cactus.
So this week will install new coil, leads and plugs.

I'll keep you posted.