Cliff. I hate to ask for advice.......but
Motor is a low comp (9:1) Buick 455. Only modifications are a 228/246 degree duration (@.050" lift) cam on 118 degree LSA installed on 113 intake C/L, and some nicely ported cast iron exhaust manifolds. Heads are unmodified Stage 1 (shaved 0.020").
Carb is a 7041540 800cfm. Idle tubes=0.038" Idle down channels=0.055" Upper idle air bleed=0.052" Lower idle air bleed=0.079" (idle air bleeds were not modified during rebuild) inlet seat=0.135" float level=0.3125". No primary rods, an old power piston was modified to seat a check ball and block vacuum source at bottom of piston well, main jets are 0.067". I recall opening the mixture screw holes a little, but neglected to record the dimension. I will need to check it. No idle air bypass.
The car runs strong (but would benefit from a little looser torque converter) and will idle at 650rpm in gear against the stock converter, but the plugs get very sooty if the car is idled for extended periods. It will eventually load up unless the throttle is opened to clean the plugs.
Would you recommend trying smaller main jets first? Or going with a hotter plug? Or maybe I have missed something?
I shouldn't ask "either-or-questions"......Cuz.
