gas cap....vented or non vented?

[hiball3985]

If I remember correctly the new EPA mandated style gas caps went into effect in California in 1970 and the rest of the country in 1971.

[meteor]

this is something I have also been trying to figure out with my ranch wagon. I bought a 'vented' cap but if you blow into it (as in air coming out of tank) nothing passes through. After reading the above posts about the regulations I thought I would try sucking on the 'vented' gas cap and sure enough, air comes in. So the cap allows air into the tank but doesn't let it escape.

I have had the cap on there for 5 years, and today I had to change my fuel pump - someone told me all that pressure could have ruined the pump. Tomorrow I will drill a hole in the gas cap...

Anybody use or adapt something else?

Matt

[RICH MUISE]

I would think the wagon/Ranchero guys would be best off trying to fing a NOS eom design cap rather than a new one that has been epa regulated. As I mentioned, one just needs to figure out when reading the description of the cap if the "vented" is refering to the cap or the tank it goes on.

[hiball3985]

I've now spent more time reading posts about vented vs non vented caps then I would have liked to. We are not the only ones with this problem, everyone from early Corvette to motorcycles to truck guys fight this issue. All opinions seem to recommend using a vented cap on a non vented tank and all have the same issue with pressure building in the tanks because the valves in new caps only vent in one direction. Many people use the drill a hole in the cap method and some add a small vent pipe to the filler neck, I may explore that sometime in the future. My latest modification to the vented cap was to remove the valve and spring completely and drill a small hole. As a word of CAUTION, if your car is kept in the garage you will notice the vented fumes linger in the air, it does in mine to a small degree but my garage isn't well sealed and I have no source of ignition like a pilot light on a water heater etc. I always open the door and let it air out for a few minutes before entering or starting the car. Time for a roof vent I guess.

Finding an OEM cap is a little difficult. I passed on the last on on Ebay, I just couldn't justify in my mind paying that much for an old gas cap and not knowing if the seller is even sure it is correct. I know a guy with with a wagon and ranchero so I'm going to go look at his and see if any of the caps are original..

[Frankenstein57]

Not sure what cap I have, but when I fill it gas spills out on turns. We built up the gasket but it still does it, I think I'll dig through my junk and see what I find.

[rmk57]

Not sure what cap I have, but when I fill it gas spills out on turns. We built up the gasket but it still does it, I think I'll dig through my junk and see what I find.

At a $1.67 a liter for premium I never have enough in the tank for it to slosh out!!!!

[meteor]

Today I dissected my 'vented' gas cap - that I now know only allows air into the tank. I first pulled out the valve and then tested the cap to see if air could still pass through from the inside - and it did. Basically, a 10-second fix and I now have a vented cap. Below are some pics of the style cap and what it looks like blown apart.

[hiball3985]

Good! I hope that works, very similar to some of my earlier experiments that had the plastic retainer for the valve. The newest cap I have is similar but the center part that holds the valve is metal rather then plastic. I still couldn't get it to vent pressure, when the gasket is compressed in the tight position the was no way for the air to get out so I still had to drill a small hole. I don't a camera available right now so I had to reuse your photo..

[canadian_ranchero]

if you read the 1957 ford parts book it says the cars on the wagon frame, the gas caps are vented.the others are not vented

[RICH MUISE]

I really liked the looks of these, so I picked up one of these "vented" caps to see if it could be fixed to a non vented..at least to not allow gas to slosh out. I'm gonna put it on my old gas tank that I can put some gas or whatever into and tip it to check for leakage.I'll let you know how that works out.

[RICH MUISE]

It leaks...thru the key hole. I don't think there's any way to keep it from leaking, the lock mechanism is pretty much open in the back. Unfortunatly there was no way to tell in the shrinkwrapped packaging. They did say vented, so I can't complain.
I did buy another one at the same time that doesn't even go on the filler neck, and was suppose to be stainless, but is zinc plated.

[hiball3985]

Rich I hope you don't end up with a cap collection as large as mine and find something that works. If a locking cap leaks that may be just what I need 

[SkylinerRon]

Vented caps are used to let air into the ever emptying tank so vacuum doesn't collapse it or the lines.
If you open the cap and air rushes in you have a problem.
Goodluck,
Ron.

[RICH MUISE]

Rich I hope you don't end up with a cap collection as large as mine and find something that works. If a locking cap leaks that may be just what I need 

HaHaaa.....Jim, do you get the feeling we're mentally challenged? You're looking for a cap that is the oposite of what I'm looking for, and well both end up with a collection that doesn't work, LOl. The obvious solution would seem to be you sending me your collection, and I'll send you mine, but there is probably something wrong with that solution I haven't figured out yet.
Actually, I'm just being stubborn. I have seen non-vented nos caps on ebay that would work (I think)...I'm just trying to find a pretty one. I would have thought with all the billet and shiney stuff out there, a gas cap for a 50's car would have been easy find.