I'm running the Motorcraft carb and an Aeromotive adjustable fuel pressure regulator. I no longer have the check valve and use a standard fuel filter. My car can sit a week and I'll give the accelerator pedal two pushes and it cranks up immediately. However, when warm, if I let it sit for more than a couple minutes, I have to crank it for a while before it starts. If it sits for more than a half hour it will start up like normal.