I use a inexpensive cap on my Comet while the really nice heavy cap hangs on my work bench. They are too easy to steal and sell at a good profit on eBay or Craig's list..
at a show a Guy that had a maverick there came up to me and asked if I wanted a new deluxe gas cap? he said he didn't need one that nice on his car so we swapped, my stock flat cap for his new deluxe cap...
The one on the left came with the car....the one on the right cost me 60.00 I think I paid a fair price for both caps...one day one of them will be just right
That is the non-vented one, originally made for that crazy vapor tank found only in the trunk of the California Emission 1970. BTW - for those asking, these caps were first found on the 1970 Grabber
Makes me want to cry...Almost picked one up for $25 on craigslist but didn't have the gas to get to the guy. :/
I ended up winning the one on ebay for way too much. I could have gotten one from someone here for like $73.00 shipped. I put a bid to what I wanted to go the highest on and I won. Way way too much and it has a scratch on the plastic that I'll have to clean up too.
I guess. Haven't had a chance to get this car started yet to be honest. Will be a long term project. I hope to do little by little on it. The cap could have waited. LOL
I don't see how it would effect the vapor recovery much. The vapor tank if still in working condition will catch fumes and send them back to get burned in the engine. If you smell gas fumes escaping from the filler you can always just plug that little hole in the cap with a small rubber plug or drop of JB Weld. Go for it.