I have a 1968 350 vette motor in a 1933 chevy. The car starts fine with an electric fuel pump and pump the accel twice. My problem is when I stop after running it for 3 to 4 miles and stop it, it does not want start back up. I thought the battery was weak put a new one in and did not help. When I fire it up its like a vapor lock. Could the timing be off. It is a double pumper Holley