Factory VENTED gas cap ?

First off I do not have a fuel leak of any type... But I do notice gas odor around the back of my pickup ( more so when full/ or warmer outside). I have the chrome OEM type Vented gas cap. Was it normal back in the day, for vented gas caps for gas vapor fumes, to be noticed from the cap ??? I would not think so! I just sprayed some PB Blaster into the vent spring of the cap to see if that helps.
Speaking of gas caps..Those of you that have replaced your OEM cap with the 68-70 Charger flip gas cap. Did you have to make any modifications ??

Yes!!! All gas caps were VENTED!! Up till the epa & mfg's made the recirculating fuel systems with charcoal canisters. Put a non vented cap on our vans & get ready to walk!! wont run far!

When I sprayed the PB Blaster into the spring valve of the cap. I manually worked the valve spring , by pushing it with a small screwdriver, so see it was stuck. It seems to be working freely.
Was It normal to smell gas vapor near the cap ?

my charger cap works fine with no fumes but i had to cut a aluminum plate to shim it out or it would hit the paint.

You may want to check the top of your gas tank for pin hole leaks AND the vent hose. If bad it will leak at a fill up. Also the hose from the filler to the tank and the pickup seal at the front of the tank.

I think that the pressure valve was stuck. Since I lubed it up, NO more fumes.