A friend put a 600 cfm Holley Quick Fuel vacuum secondary carb on his mostly stock Chevy 350 engine. This is in a very stock 1978 Malibu, auto trans. It does have headers. We got the idle nice and smooth, at around 650 rpm, with 20" idle vacuum. The vacuum advance is hooked to ported vacuum. But there is a hesitation off idle. WOT is fine. I know dick about Holleys, and he knows even less. I suspect the accelerator pump. I read up on the pump adjustments. I get the .010" gap at idle, and the .015" gap at WOT. It is the accelerator cam that I don't understand. What color would work best for this set up? My reading indicates the blue cam, in the #2 hole, would give the most volume fastest. I don't know what color is on it right now. I need to check that. If this was your car, what color would you use?