Vented gas cap?
 

Should I be using a vented gas cap on my '48 F-1? I can't find any reference to this subject in the Ford manual. I've been running a non-vented cap, but its gasket is shrunk and doesn't seal all the way around. I don't know of any other way for the tank to vent. The filler pipe does not have a vent tube. What're your thoughts?

Re: Vented gas cap?
 

Well, I finally found a parts book reference - listing a "cap assy, - fuel tank filler, ventilated type". No more mystery.