So, my car is back from the shop, with little improvement. This problem
is not new, but I thought that it could eventually be tuned away. Guess
not. My mechanic tried various different things (including changing the
accelerator pump position), checked for leaks and such, and found no
apparent problems with the carbs (Zenith downdraught, 36 WIP3),
ignition, timing, or motor in general. This is a real head scratcher.
Here's what he thinks might be contributing to the problem: as the
carb's come from the factory, they are set so that the initial throttle
opening (which is a function of the accel. pump, right?), is very lean.
Upon an engine rebuild (which I think mine has had done), the cylinder
size is typically increased, so that if the same jet as before is used,
the mixture is now too lean, causing the 'burp' that happens with the
initial throttle application. Does this make sense? Or is it possible
that somewhere along the way the jets in the carb were changed? Short of
getting a box of various sized jets and spending a few days on it, is
there some 'easy' way to check this? As I said before, other than that
little 'burp,' it runs great the rest of the way through the RPM range.
Idle is fine, too. Makes a good case for fuel injection...
Thanks for all the input!
Chris
'62 SII
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