I am running a Holley 650 double pumper on a 350 with aluminum manifold and cast iron heads. If outside temperature is over 70-75 degrees, I have serious troubles restarting engine. Will restart well if done immediately after shutting off, or I have to wait 20-30 minutes. I have been told that heat builds up in the bowls, boils the fuel and basically floods the engine. This theory makes sense because when the engine does start, there is a lot of dark smoke for a few seconds. I have eliminated by mechanical pump and routed all lines away from exhaust ( run Holley blue pump with regulator). I also have a 3/4 inch phenolic spacer under the carb, and I have tried lowering the float levels, but none of these things have helped much. Does anyone have any other suggestions like changing needle and seat valves, power valves, different floats, or alternate plumbing options? Someone suggested using an MSD 6Al with new distributor (currnetly have Mallory Comp 9000 with Mallory coil), could this make a difference in my restarting?

I want to add P1SC through the carb, but not until I can get this problem under control.

Other people do not seem to have this must trouble, maybe I should just try a different/new carb?

Any ideas might help.

 

Does no one have this problem? Or does no one have a solution?

 

Does your regulator have a return to the tank? If not I would try that. My car does this slightly, it will always start though. I have a mech pump with no return and no spacer.