I changed out the engine from a 350 to a 383 stroker the 350 had a fuel injection but I went back to carb on the 383. Fuel pump was left in the tank fuel filter about half way between front & rear of the car. I added a regulator to get the fuel pressure back to 6.5 psi. Fuel lines could be to close to heat from the machenical pump to the carb. I do have another filter before the fuel gets to the carb I've been told this could be the trouble.