So, I guess I would like a little more info before I would start throwing parts at it. First, do you run a fuel filter or the correct fuel separator with the fuel return line to the tank? If you have a fuel filter, is it before or after the pump? Do you use the high idle solenoid correct for 6bbl cars? Have you checked to make sure that all your clamps and fittings are tight? I have a 6bbl car, with a fuel filter in-line before the fuel separator, a mechanical pump, and the high idle solenoid in working order. I pump my car twice and turn it over, it doesn’t crank very many times before it fires up, even after sitting. Now, on first startup after winter, I’ll splash a little fuel down the center carb before it try it, but that’s the only time I have to do that. I run a 50/50 mix of 110 Turbo Blue and 93 octane ethanol free “rec fuel”.