Originally Posted By BradH
Hmmm...
-> 440-ish cubes with "big" heads that work better on 500+"
-> moderate CR
-> 260+ at .050" street roller
-> limited stall speed
-> street-tuned(?) carb w/ 1.56 venturi & downleg boosters
...

Starting to look to me like a mismatch of parts, of which the carb is likely one of the "What's wrong with this picture?" items, along w/ the converter being too tight. The carb may be workable, but I'll take a s.w.a.g. that the way it's set up right now is... uh... "wrong".

FWIW, the backfire upon WOT acceleration (IIRC what you posted originally correctly) would point me to verifying fuel bowl levels are high enough & accelerator pump passages & pumps are clear and working properly, and then making sure none of the air bleeds are plugged up (dirt or whatever).

My twocents (which are usually only worth about $.0125) is to tear it down completely and get (buy/borrower) the proper tools to measure all the circuits & orifices so that you KNOW what the current tune is. Post 'em, and get some feedback on what makes sense to change from there.

This is still a pretty basic carb... it can't be THAT effed up.


I had the carb apart and physically went through everything. I did not go to the extent of measuring all of the orifices though...I've never actually done carbs to that point.