Looking for an education in fuel tank venting

Venting keeps the air pressures in the tank at atmosphere. I just went through this; I had a one way vented cap so it would suck air as the fuel level decreased, but it was building pressure and causing my carb to run rich by blowing fuel past the needle. I drilled a hole and welded or epoxy a piece of 3/8" fuel line a couple inches down on the top of the filler neck and ran a vent out a hole in the tail panel with a chevy PCV valve pointed up, for a roll-over valve.

It's not a big deal, if you need one, make one.