71 flip-open gas cap on 66 mustang
I have a '66 Mustang that I put an original '71 flip-open Mach 1 style cap on. I'm using the original style '71 cap where the seal is part of the flip-open lid not the later style that has a separate cap under the flip-open lid. The '71 cap is not vented and because of that the '66 tank is developing a vacuum inside. I know that others have used this '71 cap on the early cars, how did you get around the venting problem?