66 Dart Gas Cap

I’ve already put on an insulator pad under the carb plus I’ve added a spacer. It’s not a stock setup as I’ve replaced all fuel lines and I’m thinking one of the issues is that the return line in the system creates pressure when dumped back into the tank. I run a Mallory electric fuel pump with a regulator and 5.5 - 6 lbs of pressure. That’s the reason I ask about the vented cap. I’m going to be switching over to a 2x4 set here shortly but was hoping to figure this out first.