1972 bug - timing and carburation problems?

I have a couple of questions about my 1972 european AB engine case VW 1300 stock.

1.) Why do I get info around the net, that the AB engine case belongs to a 1600cc engined bug? For a fact I know that mine is original 1300. Was that only in the US? 2.) At what degrees should I time my engine? Vacuum on, off? 3.) How do I properly tune my carb? Can't remember exactly the model though, it's a solex pict with both volume and bypass screws.

So far I was unable to tune the thinge. The carb was rebuilt, I have checked it I-don't-know-how-many times, but the car keeps stalling, jumping, etc while it's cold. This gets better when the engine gets hotter, but it doesen't disappear completely. At more RPM it goes fine, but especially uphill it has problems. What else... the engine was rebuilt, has good compression, the collector heater pipes are clear now, I think there are no leaks... must check for sure. The coil is new, the wires too.

Please HELP! Thanks!

Damjan

Reply to
Damjan Mozetic
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AB case could be built as either a 1300 or 1600.

To find out the timing spcs, you *must* determine the distributor in use. It should have a part number stamped on the side. Then go here for info:

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Speedy Jim

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Reply to
Speedy Jim

Probably.

Assuming you have a stock single vacuum distributor, time it with vacuum hose OFF and at 7.5 degrees advanced.

Adjust VALVES first. Then ignition timing. Without those done first, there's no point in adjusting the carburator.

Then follow these instructions:

1) drive the car around to get the engine fully warmed up 2) turn the accelerator lever stop screw out, until it no longer touches the stepped, freely moving choke plate. You know teh plate with steps in it that moves with the choke. Keep the stepped plate in the "choke off" position with your hand or tie it dow to keep it there, then turn teh lever stopper screw in again until it JUST starts to touch the lowest spot on the stepped plate. Then turn it in another 1/3 - 1/2 turn, and leave it there forever. You will never touch this screw again. 3) start car (if it wasn't running yet), use the larger, top adjuster screw on the left side of the carb to bring idle up to near "normal" idle speed. 4) let teh car idle for a while, so the engine speed smoothes out. Then turn the smaller, bottom screw in (that's your mixture screw) until the rpms start to drop. Go slow, 1/2 turn at a time and listen carefully. When the rpms start to drop, you start turning the mixture screw back out, very slow. Turn it out until the idle speed stops rising. This is hard to spot, especially with a worn carb/engine. You are trying to find the exact spot where the rpms stop rising as you turn the mixture screw out. Find that spot, and then turn teh mixture screw OUT again another 1/4 -1/3 turn.

5) adjust idle speed to where you want it to be, 900 is good. Now you are done.

Repeat this procedure after a few days of driving to make sure you got it right.

This is called "Tuning by ear", and the results may vary. People hear things differently, some people can pick slight rpms changes easily while others can't. There's a lot of room for interpretation in these instructions, and this is why I must add that this is NOT ACCURATE. A stock engine will live ok, but I would still recommend taking it to a mechanic who has an exhaust gas analyzer. Those won't lie, you can adjust the mixture precisely to where it needs to be with that. With the "by ear" adjustment you can get close enough to actually drive the car to the mechanic :) Or you can cruise around for a week if you can't take it to a mechanic just yet.

I'm tempted to say that it is no big deal on a stock engine and you could leave it like that and drive happily ever after, but I won't. I STRONGLY recommend the analyzer test for any aircooled VW engine, just to be sure. This is in my opinion, CRITICAL on high performance engines.

Jan

Reply to
Jan Andersson

I found out that I cannot pass emissions if I do that. I need to go IN half a turn from the highest idle point to get under the 4.5% limit :)

but mine is a H30PIC carb, maybe its just different...

Reply to
Eduardo Kaftanski

That setting makes it intentionally rich to be on the safe side. Which is why I recommended an analyzer to finish it off.

Each carb is a bit different.

I forgot about the emissions tests, here it's not required for beetles due to old age.

BTW, now that you mentioned it, I started doubting my words.. maybe it was a quarter turn IN instead of out. I just wonder.. I quoted from memory late last night. Better double-check that.

Jan

Reply to
Jan Andersson

Maybe I skimmed over your message too quickly - but what kind of air cleaner do you have? The stock one is best in winter. Could it be the choke? I have a cheap after-market air cleaner, and I HATE it right now (about 20F in Atlanta)...

Reply to
pmbedard

Static timing gets you close. Strobe timing is more accurate.

That Damn Jan

Reply to
Jan

If you meant me, I have the stock air cleaner and yes, I also doubt the choke doesen't work too well, even though it does open while the engine gets hotter.

Jan, I'll try that. Thanks for the detailed info... even the books don't explain it so well :) I hope that this time will be the last time I try to calibrate the carburettor, because I must have tried to do it a million times... unsuccessfully.

My distributor is the stock one, with vacuum. Do you tune the distributor statically or with a strobe light? I have done it only statically up to now. Any hints?

PS. In Slovenia oldtimers do not need to do the emissions tests, so it doesen't really matter to get exact, as long as it runs fine.

Damjan

Reply to
Damjan Mozetic

Jan is right except for that last part. You should turn the screw back=20 IN a bit from the spot that the revs stop rising.

Reply to
Olli Lammi

Jan is right except for that last part. You should turn the screw back IN a bit from the spot that the revs stop rising.

Reply to
Damjan Mozetic

Ok. The same in my words.

  • adjust the throttle lever screw as Jan said
  • turn off the engine
  • turn the smaller screw in all the way (gently and not tight, just = where it stops turning)
  • open the smaller screw two and half turns (complete revolutions)
  • turn the engine on and let it idle for a while and adjust to proper = idle=20 by turning the bigger screw (850 rpm or by ear)
  • carefully start opening the smaller screw by 1/2 turns. Listen = carefully after every turn, what it does to the idle speed. Open the screw as long as the revs do not go up anymore.
  • now that you have found the place, where the revs stop rising, turn the screw back in carefully 1/4 turn at a time as long as the revs = drop a bit=20
  • leave the small screw and adjust the idle to 850-900 rpm with the = large screw

Hope this helps.

Reply to
Olli Lammi

True, as I pointed out in an earlier replöy to this. My mistake, sorry.

Jan

Reply to
Jan Andersson

Ok. The same in my words.

  • adjust the throttle lever screw as Jan said
  • turn off the engine
  • turn the smaller screw in all the way (gently and not tight, just where it stops turning)
  • open the smaller screw two and half turns (complete revolutions)
  • turn the engine on and let it idle for a while and adjust to proper idle by turning the bigger screw (850 rpm or by ear)
  • carefully start opening the smaller screw by 1/2 turns. Listen carefully after every turn, what it does to the idle speed. Open the screw as long as the revs do not go up anymore.
  • now that you have found the place, where the revs stop rising, turn the screw back in carefully 1/4 turn at a time as long as the revs drop a bit
  • leave the small screw and adjust the idle to 850-900 rpm with the large screw

Hope this helps.

Reply to
Damjan Mozetic

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