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Discussion Starter · #1 · (Edited)
Some background: my bug (72 with a 1600) was running well but it wasn't running as well as it could have because it had the wrong carb (too small), and wrong distributor.
I've already put the correct stock distributor on it and it works well.

I recently got the correct carb (34 pict--3) and set about putting it on, however I lost one of the manifold nuts and feared it fell down the head so I pulled the engine out to inspect. I discovered it hadn't fallen down (no need to take head off because I could clearly see it wasn't in there) so I put the engine back (with new manifold and carb).

Now when I try to start it up it idles to fast (about 2000rpm). The manual says it could be caused by the automatic choke not switching off (it's fine - I've even changed the heating element) or it could be the choke valve or fast idle cam sticking. Well I haven't got a fast idle cam on this carb (AFAIK), and I can't identify the choke valve :confused: I've found it on a diagram but I can't recognise anything like it.

In the meantime I've taken a spare 34 pict-3, rebuilt it (albeit in a rush), and tried that but now the engine won't fire at all with that carb on. I can only guess that I must have overlooked something in the rush to rebuilt it, and some component is sticking or broken or something.

Any ideas anyone?
 

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Discussion Starter · #3 · (Edited)
is the float chamber full of fuel ...and does the accelerator jet squirt fuel when you open the throttle?
On which carb? - the fast idling or the non-starter?

I think both chambers were full, the fast idler certainly was quite full because I took the lid off later to check it out (off the car).
I don't know if the jet was squirting though. I didn't realise I could take the lid off while running... I thought it might be dangerous.

Thanks for your reply by the way. :)
 

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Tech Guru/Mr VZi '06
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I didn't realise I could take the lid off while running... I thought it might be dangerous.
You're right thinking that, ^.
Have you adjusted the first carb to the basic settings before you ran it?
Air leaks on the inlet manifold can cause fast idle.
Incorrect ign timing can too.
A couple of clear pics of the carb would help perhaps.
 

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Discussion Starter · #5 ·
You're right thinking that, ^.
Have you adjusted the first carb to the basic settings before you ran it?
Air leaks on the inlet manifold can cause fast idle.
Incorrect ign timing can too.
A couple of clear pics of the carb would help perhaps.
I did adjust the first carb before running.
The timing was set beforehand too.
Ok - I'll put the carb back on and take some pics.
What you said about leaks in the inlet manifold makes me worry. I wonder if there's a crack or something in it. I remember it was a bugger to get into place. And I remember reading a thread on here recently about using the good genuine rubber tubey/joining bits inbetween (which I think I have on there).
I got it from a mate with a spare 34 pict-3. Thinking about it further I didn't change the parts of the manifold which attaches to the heads. Does that matter though? - wouldn't they be the same for the smaller manifold for the smaller stock carbs?
 

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Discussion Starter · #6 ·
I did adjust the first carb before running.
The timing was set beforehand too.
Ok - I'll put the carb back on and take some pics.
What you said about leaks in the inlet manifold makes me worry. I wonder if there's a crack or something in it. I remember it was a bugger to get into place. And I remember reading a thread on here recently about using the good genuine rubber tubey/joining bits inbetween (which I think I have on there).
I got it from a mate with a spare 34 pict-3. Thinking about it further I didn't change the parts of the manifold which attaches to the heads. Does that matter though? - wouldn't they be the same for the smaller manifold for the smaller stock carbs?
Perhaps I could do some quick and easy test to check for manifold leaks? I remember spraying wd40 around passat injector seals to check for leaks (the engine tone changed). The same thing wouldn't work here because it's not idling properly. Or would it?
 

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Tech Guru/Mr VZi '06
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I did adjust the first carb before running.
The timing was set beforehand too.
Ok - I'll put the carb back on and take some pics.
Pics? Mail them if it's easier, although I won't see them until tonight.
Exactly where do you have the adjuster screws set to?
Timing done static, or with a strobe?
 

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Discussion Starter · #8 ·
Pics? Mail them if it's easier, although I won't see them until tonight.
Exactly where do you have the adjuster screws set to?
Timing done static, or with a strobe?
I'll be able to take some pics when I get home tonight and put the carb back on. I'll post them on this thread.

I adjusted the volume and byoass screws exactly as the Bentley manual says. I fettled with them endlessly in vain afterwards though, so I'll be resetting them again to the initial state before I put the carb back on.

My father timed it first whilst the engine was out and on a bench, and then he timed it again with a strobe when we put it back in (although I noticed he didn't wait for the engine to warm up completely before doing this, but that was probably because it was idling poorly).

I think I will have to time it myself when I set about the engine again this evening.
 

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Well I haven't got a fast idle cam on this carb (AFAIK), and I can't identify the choke valve :confused: I've found it on a diagram but I can't recognise anything like it.
The fast idle cam is the piece of metal on the end of the choke flap shaft with the "teeth" on it that the throttle stop screw rests against. it keeps the throttle arm from fully closing until the autochoke has come off.

I assume the choke valve refers to the actual choke butterfly itself.

Dave.
 

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Discussion Starter · #13 ·
You have all the bits you said you didn't seem to have, ie fast idle cam etc., and the choke is set roughly right.
The screw shown below isn't set correctly though by the looks of it. Set it as shown on the pic I posted here...
http://www.volkszone.co.uk/VZi/attachment.php?attachmentid=6210&d=1200227792 then try it.
I'll look at your pics more closely later.
First of all thanks for helping.

About the fast idle cam, I misread (one of the many) exploded diagrams and I thought that the fast idle cam was that extra bit of metal lever that sometimes accompanies the fast idle cam. (If needed I can show a photo to explain better).

About the screw set incorrectly: I foolishly overlooked that! I'll set that correctly next.
 

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Discussion Starter · #14 ·
Some comments/questions....
The generator terminal does need sorting out. I shall get that done.

The loose hose goes to the from of the air filter box on top of the carb (I think!...).

The condenser pipe is quite inadequate - it's fuel line. It is loose at the condenser end - no jubilee clip. I need to change that pronto too.

I didn't realise I had the manifold clips in the wrong position. Where should they be?
 

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I know from your point of view that this is a slow way of fixing it, but for me it's easier to correct each individual fault as we go and see what the results are, otherwise I have to write a manual explaining all the possibilities in one go. ie. 'if that doesn't work try.....', and ' if that makes it better then try.....' etc etc.

The mark on the first choke looks a peculiar shape but it could be correct. The mark on the second choke may just be a centre dot as below. The marks are a guide though, on old choke units they may not necessarily line up exactly.
 

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The generator terminal does need sorting out. I shall get that done.

The loose hose goes to the from of the air filter box on top of the carb (I think!...).

The condenser pipe is quite inadequate - it's fuel line. It is loose at the condenser end - no jubilee clip. I need to change that pronto too.

I didn't realise I had the manifold clips in the wrong position. Where should they be?
The "condensor" is the vacuum advance unit. The actual condensor is the small round cylinder to the right of the vacuum can.

The pipes going to the vac advance unit and the air filter must be the correct size (narrower than what you have on there) otherwise you might as well not have them, because if they can't make a perfect seal then they won't work at all.

The clips are normally fitted with the screw heads uppermost, but I think that's only for aesthetic reasons - I'm sure Moby will put me right on this if there's another reason !.

Dave.
 

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Discussion Starter · #17 ·
The "condensor" is the vacuum advance unit. The actual condensor is the small round cylinder to the right of the vacuum can.

The pipes going to the vac advance unit and the air filter must be the correct size (narrower than what you have on there) otherwise you might as well not have them, because if they can't make a perfect seal then they won't work at all.

The clips are normally fitted with the screw heads uppermost, but I think that's only for aesthetic reasons - I'm sure Moby will put me right on this if there's another reason !.

Dave.
Damn it! :eek: Now I look like an idiot! I knew that it was the vacuum unit. :eek: I don't know why I wrote condenser.
Actually I do: it the same reason that I misread the diagram about the fast idle cam, and the reason I'm struggling to get this engine running despite having every manual I need at my fingertips. It's a frustrating fault I have with reading and getting things mixed up or blocked out. Probably dyslexia.
 

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Discussion Starter · #20 ·
I know from your point of view that this is a slow way of fixing it, but for me it's easier to correct each individual fault as we go and see what the results are, otherwise I have to write a manual explaining all the possibilities in one go. ie. 'if that doesn't work try.....', and ' if that makes it better then try.....' etc etc.

The mark on the first choke looks a peculiar shape but it could be correct. The mark on the second choke may just be a centre dot as below. The marks are a guide though, on old choke units they may not necessarily line up exactly.
Your help is extremely appreciated, and your common sense approach is perfect. Thank you again.
I very much appreciate that you must be miffed with spending your time answering dumb questions which could just as easily be answered if the questioner just RTFM'd.
 
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