Gas cap numbers?

[hiball3985]

I'd love to find one of those old type Vented caps for my Ranchero, but they are like trying to find hens teeth..

[RICH MUISE]

DJ...thanks for posting that. I loved the note that says see other boxes for more applications, lol. What is the difference between the g22 and the pictured g31?
Am I correct that those designations are for the cap design, regardless of manufacturer? In other words all of the manufacturers used the same part number?

[djfordmanjack]

Rich, I think these are Stant numbers. obviously the G means gas, as I have oil filler caps too and they read SO *** (Oil).
Unfortunately I don't have the G22 cap anymore as it's on the Merc I sold. Maybe I can find pics. If you need dimensions or more pics of the non vented G31 cap I have ( fits 53-63 Ford pssgr) let me know.

[canadian_ranchero]

the gates number ends in 31.maybe the end numbers are the same?

[RICH MUISE]

And the Robertshaw number the ebay seller actually had posted is RG-31.

[djfordmanjack]

Interesting. I never heard of standardized gas caps/numbers before. but in Europe we have them. Actually here they are refered by the inner filler neck diameter. some also fit the American sizes and they are cheap. made of neat aluminium, much like the old tractor tank caps or else.
I need to use a non vented cap on my Del Rio, since I am going to move the filler neck inside and add a vent hose.

[clusterbuster]

Received the G31 gas cap today and it does not fit--way too loose. My tank is an aftermarket tank so I guess that is the problem. I am going to give up on a new cap, as I made two gaskets out of a truck inner tube, doubled the gasket, and that tightened the old cap up nicely. Even when I tripled the gasket on the new cap it was too loose. Beware if you have an aftermarket tank and look for a good gas cap fit.

[RICH MUISE]

Well, shoot...just when we thought we had the problems resolved...at least for the non vented. Where was your tank purchased? Now I'm going to have to unmask my tank on the car to see if I have the same problem. My tank was from auto city classic. I'll post the results.
EDIT.............I lucked out. The Stant G-31 cap I got fits the new tank as tightly as the old tank. Now I'm especially curious to hear where your tank was from. Also, Cluster, what brand G 31 cap did you get?
Also, was thinking if I had the same issue, I'd look into bonding a ring to the filler rather than modifying the cap....Maybe a nylon/mylar/plastic type material or aluminum. I'm thinking rubber is gonna wear out pretty quick.

[RICH MUISE]

Cluster...if you want/need, I can dig out my micrometers and calipers get get some dimensions so we can compare caps and filler necks. It would be nice to nail down the cause of some having issues getting caps to fit.

[clusterbuster]

Rich, I bought the new cap from myestatesales1989 on Ebay. It is the Robert Shaw RG-31.  No need to measure Rich, as I will just make do with the thick double rubber gasket on the old cap. I contacted the company that I bought the tank from to see if they can get a number for a cap for their tank. I deleted the company, and I can't remember the name I sent to today. Will try to dig it up later.

[clusterbuster]

Found the company faster than I thought. Went back into my history and found it was Paceauto1 that I bought the tank from. It fit perfect and was made in Canada I believe.   $181.21 free shipping.

[KYBlueOval]

This gas cap thread is very timely. About a week to 10 days ago, I contacted Stant via E-mail asking them what gas cap was correct for my Ranchero. They replied that their catalog did not go back that far. When these most recent postings with the G-31 etc. part numbers appeared I contacted them again and quoted the "Fitment" list as is shown on the two boxes. Yes, I understand that the numbers quoted are for non vented caps, but my thought was that if in fact these two Stant numbers were correct, perhaps Stant could look up the specs for the non-vented cap and it would lead them to the specs  and part number for the vented cap that Wagons and Rancheros need. I offered to send them the filler pipe from my Ranchero ( on the condition I got it back! ) so they could find the correct cap. That was a day or so ago, and I've not received a reply as of this posting.
When I receive a reply, I'll let y'all know.
John

[canadian_ranchero]

the gates number for the s/w, ranchero is 31640.this one is a shallow cam.the newest listing i have says it fits full size fords,merc and t-bird for 1970.also have a mcquay-norris number dgf 40.i was a partsman in the 90's and have ford and jobber parts books,the oldest going back to the 30's.here is a picture from the gates jobber data guide showing the spex on the 2 gas caps in question.hope this helps

[hiball3985]

This gas cap thread is very timely. About a week to 10 days ago, I contacted Stant via E-mail asking them what gas cap was correct for my Ranchero. They replied that their catalog did not go back that far. When these most recent postings with the G-31 etc. part numbers appeared I contacted them again and quoted the "Fitment" list as is shown on the two boxes. Yes, I understand that the numbers quoted are for non vented caps, but my thought was that if in fact these two Stant numbers were correct, perhaps Stant could look up the specs for the non-vented cap and it would lead them to the specs  and part number for the vented cap that Wagons and Rancheros need. I offered to send them the filler pipe from my Ranchero ( on the condition I got it back! ) so they could find the correct cap. That was a day or so ago, and I've not received a reply as of this posting.
When I receive a reply, I'll let y'all know.
John

I'm not sure I would trust sending my filler neck off to someone. not with my luck 
I found two different caps to fit my Ranchero that are vented. My problem is they only vent in one direction, letting air in but don't let pressure out. No NEW manufactured caps allow venting, Fed regulation since the early 70's. This is a common problem people with early Ford pickups, Corvettes and other also have. Many of these people including myself just drill a small 1/16 hole in the cap to let it vent. Not the best solution but I haven't found a better one yet.
With out the vent hole, in my area and temps in the 100+ the tank builds so much pressure that when you remove the cap the air/fumes and sometimes gas comes flying out and I had heard the tank oil can at times. It no longer does that with the hole.

[Wirenut]

Rich, would you mind checking the thickness of the lip inside the gas tank filler neck. Mine is 7/16''. I replaced my tank years ago and have tried a few differant caps but no luck. If yours is the same I will order one of the caps like yours. Thanks