My 1967 S3 has been running very rich since I bought it last October, with
an occasional backfire & frequent spitting through the intake. Yesterday, I
tried to lean it out using the mixture adjustments (it has Webers) as
suggested in the shop manual & found that the rear adjustment seemed to
have no effect at all. I can screw it closed or well out with no change in
engine speed or behavior.
Does anyone have an idea as to what the cause might be? My experience with
other cars leads me think it's a leaking accelerator pump, float level,
needle & seat, or some other internal problem. I'm hoping that a minor
disassembly will uncover it. I've never worked on a sidedraft Weber but
have worked on SU's, Carters, & Hollys. My impression from the manual is
that the Weber is relatively simple to work on. Is this correct or should I
take them to a specialist?
Re the mixture problem, I set the timing & checked compression (175# +/-
3#). The car has a Bendix fuel pump with a pressure regulator set at 2 lbs.
The rear plug is black but not damp. The others are ok. No major gas smell.
At a fairly low idle speed, it often seems to miss on 1 cylinder. On the
road, it feels strong on acceleration but pops & sputters at a constant
speed.
Sorry for the long note - imbedded are just 2 questions. Why would the
mixture adjustment have no effect and can a mere mortal get a Weber back
together again once he opens it?
Thanks.
John Coelho
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