Anyone know where the carburettor adjustment screws (idle, mixture etc)> are located on a 1988 Polo 1050cc fitted with the Pierburg single barrel> automatic choke carb (I think it's the 1B3). It's been a while since > I've tinkered about with engines fitted with carburettors, so before I> take a look I just wanted to know where all the various adjusters were.> Thanks.

TBH, it would be far better if you actually explained the problem(s)> you are currently having if you want decent advice here.

It's my nephew's and from what he tells me over the phone it sounds like > an automatic choke problem. He says the revs are low & cutting out when > started from cold but runs ok once warmed up, but the revs still seem a > little low . I've just had a quick look to check all the pipes and > connectors are secure and I noticed that even though the car has been > standing for several hours the choke flap remains fully open and doesn't > appear to be closing. Loosening the 3 choke assembly screws I can rotate > the choke housing a good inch clockwise before the choke flap starts to > shut. As a trial & error measure I adjusted the choke flap so it's about > half shut and it started up fine and ran smoothly.>

Once fully warmed up I connected a tacho and the revs do seem a bit low at > 600rpm. I've not got a manual for this car but according to Autodata CD > the idle speed should be around 800 + or - 50. However they assume it's > fitted with a Weber 32TL carb and not a Pierburg! I was going to make a > slight adjustment to the idle speed (making a note of the original > position). I can see a screw on the left hand side of the carb (as you > look from the front of the engine bay) that hits the throttle stop. I'm > assuming this is the idle speed adjuster but the end of this screw doesn't > appear to have a slot to adjust it. It's a bit awkward to see the screw > head properly but is it fitted with a tamperproof cap? I have read that > these carbs are a PITA and will keep an eye out at the local scrapies for > a Weber replacement.>

If you have no CO meter, generally the technique is to adjust the mixture > screw> by gradually turning it in until you get max idle rpm, then turn out a > fraction> (1/8th turn maybe). You then adjust the idle air-by-pass screw for correct> rpm. Screw in for slower and unscrew for faster.>

There is an idle speed boost valve fitted on the carb for Volkswagen HZ > engines.> Maybe yours is faulty.>

If you fancy keeping the 1B3, it will probably pay you to buy the Haynes> "Automotive Carburettor Manual" or photocopy the appropriate pages. There> should be some detail in your Haynes Manual for the Golf too.> There's at least two of the Haynes Auto Carb manuals on E-bay at the moment,> items 4541957546 (ends Sunday at 19:49) and 8301709064 (7 days left). > List> price is Ј19.95 apparently. There are others that deal with motorbike carbs > and> Weber - maybe others too.