Well I can't get a response from the Impala Forums so I'll try you guys. Any help is greatly appreciated.

In my '66 Bel Air, I have a 4 bolt main 350 out of a 1970 C10. Its bored 30 over, RHS Pro Action heads 180cc intake runners 74cc chambers, manley 2.02/1.60 valves, Comp Extreme energy cam .463/.469 lift 262/270 duration, Manley flat top pistons approximately 11:1 compression, Edelbrock torker II intake, Holley 650 double pumper 70 primary/72 secondary, carter super strip fuel pump, GM HEI with accel super coil. Timing is 4 advance at idle (if i remember right) and 35 full advance at 3,000 rpm

When the engine was dyno'd, it ran lean until they put the 70 primary jet and 73 secondary jet into the Holley and when it was in the car it was running really rich, the exhaust pipes were black after a tank of fuel through it and the plugs were black. It started running rough and I went down to a 68 primary/70 secondary and slowly worked my way up. Come to find out one of the plug wires was arcing across. So I changed that and now it idles fine back at a 70 primary. But now with a 72 secondary jet it stumbles when you step on the gas. So I put one size bigger primary squirter, and one size bigger secondary squirter in it, and that helped a little bit but it still stumbles when you stomp on the gas.

The motor was broken in on the dyno, has about 6 or 7 dyno pulls on it, and probably 500 miles in the car. Fuel pressure is between 9 and 10 psi. I've changed jets so many times I'm sick of it. I'd like to be able to stomp on the gas and not have it fall flat on its face. Any help is appreciated.