correct rad cap?
 

Question:
Can anyone confirm the type and design of rad cap correct to 1970 Formulas & Trans Am's?
(I am guessing that all models used it regardless of model/engine, and it's a year by year thing)

This past year I grabbed an old rad cap from a scrap yard;
It's an older RC-15, and from a cursory search, this appears to be the correct type for my car.

Am I correct in understanding that the Delco RC-15 rad cap had design changes during it's manufacturing lifespan?

I found this nice post:
https://forums.maxperformanceinc.com...&postcount=424

I did some further searching, and it looks like you can get a reproduction which has the indented(?) rivet, and some have a flat.
Is one of these rivet styles wrong - and maybe used by a repop company to keep cost down?

I soaked mine in rust dissolver, and it came out pretty nice;
I doubt mine would pass a pressure test though - as the brass ring (gasket?) has a crack in it.

Any advice or thoughts shared are appreciated.

The indented rivet style is correct for the 70 birds. I'm not sure when exactly when the rivet head changed to the flat version.

PY member Norwood recreated them for us a while back. Not sure if he still does this or not but he did a great job as always.

1970 cap
 

I believe this is 100% stock on my l65 esprit 400 with if Harrison radiator

There is a hollow rivet version which is the earlier style correct for 65-67, I believe. The solid rivet version like in macho's picture above is correct for 68-72. Here is another picture of one I just replated.

cap
 

you can restore a cap?

Yes. There is a place that does them. They completely take it apart, plate, and put in new rivets. They charge $150.

I did this one myself without removing the main rivet. Looks good on the top side. The hard part is figuring out a procedure to replace the rubber gaskets so it will seal and hold pressure again.

And you did replace the seal without removing the rivet? Are you willing to share how? I have one that needs a new seal.

Sure, but it is more complicated than I thought it would be. These caps are constructed with 2 rivets and 2 rubber gaskets. The big rivet you see holds the spring and main components together. I did not touch that. On the underside there is a small 1/2" metal cup in the center that is loose and spring loaded from inside. There is a rubber seal under there that is what holds the pressure. There is a small brass step rivet in there that needs to be drilled out to replace that small gasket. The center piece with the lip that holds the large rubber gasket is just pressed in. You can dig out the old hardened gasket and work that with a flat blade. Once you remove that pressed in piece, you can get ahold of that small rivet to drill it out.

Attached are some pictures.

I have not been able to find the step rivet with the needed specifications so I bought some brass 1/8" rivets online and grind and cut using my drill press. It's kind of a lot of work for a radiator cap but something to play around with if you're bored.

thanks everyone for your replies.

I have a very generous member hooking me up with one.

I figured that I'd share a link to another discussion I found last night which is hosted here on this same very subject, and share some pictures of the rad cap I have (I did a light cleaning of it post rust dissolver soak).

LINK

I don't know if sometimes these were stamped lightly/poorly, but the bottom of all the letters in "REMOVE SLOWLY" fade into nothing - and the counter clockwise arrow that I believe should be above that same text is barely visible at points to the naked eye.

That looks like the hollow rivet style used up through 67. This is based on info I have found on multiple sites.

/\ although I am confident you're trying (like often I do) to be helpful, it seems your application contradicts the other thread...

???

Yeah, I see what you mean. I searched on several boards including Buick, Olds, Chevelle, and Camaro and was seeing consistent information with the styles and years. In your link, the very last post mentions the flat rivet for 70 from a Camaro board.

Also, if you look at the various original and NOS big ear caps on Ebay, they are labeled pretty consistent with these year breaks. You can even see the earlier 64-65 caps that have a different stamping but still use the hollow rivet indicating that rivet was an earlier incarnation.

Sometimes I have seen that flat rivet with a small dimple and sometimes not. Not sure what that difference is about.

Sorry for the horrible pic, but does this resemble what was once a 70 cap? I'm not able to go see it myself in person right now, so this is the pic I got of it lol

Yep, looks like it.

Cool. I'll definitely get better pics soon to confirm. If it is, do you think it's worth restoring?

Probably not. It looks pretty crusty and will likely be very pitted. The rnewer repops are decent unless you are doing a concours level resto.

I'm trying to get it pretty close to concourse. It'll be driven, but it'll be the only car I own that's super correct, so it be cool to have.

Are the reproduction ones super obvious they're not original? I've only just started looking at them. I'm still a ways off from needing one, but getting closer every day!

I think there is a newer version out there where the stamping looks really good but the rivet isn't exact. Maybe it's the inline tube version. You can find restorable caps at swap meets and sometimes for only a few dollars.