'70 BB a/c brass expansion tank ???'s

[George W.]

First question: How and when were these painted? Were they painted before installation or after; with the brackets and/or hoses installed or not; was the cap opening masked; gloss, semi gloss, or flat black? Second question: Does the cap have a brass rivet in the center with RC stamped in it? Thanks all, G.

[John H.]

Re: '70 BB a/c brass expansion tank ???'s

They were received at St. Louis already painted.

[George W.]

Re: '70 BB a/c brass expansion tank ???'s

Thanks John. Do you know if they were painted with the brackets installed? Were the brackets painted, and if so, were they painted on the inner fender side? Mine appears to have been painted with the brackets installed, and some of the paint seeped under the straps. There appears to have never been any paint on the back (attachment side) of the brackets. Does this sound correct? Mine appears to be finished in flat black; is this corrsct? Thanks again, G.

[Joe L.]

Re: '70 BB a/c brass expansion tank ???'s

George------

The tanks were not painted with the brackets already installed. The retaining brackets were seperate parts that were so-supplied to the assembly line. The tank was another seperate part that was supplied to the assembly line. The tank was supplied already painted and the brackets were supplied already painted. All these parts "came together" on the car. Actually, I would expect the sheen of the black paint used for the tank and the brackets to be slightly different since they were painted at totally differnt sources. However, I've not really paid a lot of attention to this.

I can only guess that the situation you have observed occurred, for some reason, after the car left St. Louis.

[Tony H.]

Re: '70 BB a/c brass expansion tank ???'s

George,

I believe the original cap was the RC-15 cap. Furthermore, the cap was made with a flat brass rivet that had a circular ridge on the top outer edge of the rivet. RC-15 and 15# were stamped in a circle on the zinc-plated cap near the right ear.

I hear there is a great article in the latest Restorer (Winter issue) on the RC-15 caps of this era. (Patrick Hulst and myself are the co-authors)

Tony

[Dave S.]

Re: '70 BB a/c brass expansion tank ???'s

Tony,
Great Restorer article. It helps clear up many of the unanswered questions. My 70 LS-5 A/C car had an RC-26 radiator cap. Should it have been an RC-15.????

[Patrick H.]

Re: '70 BB a/c brass expansion tank ???'s

Dave,

Too bad you don't have it, or I'd swap you the RC-15 my 72 has now for the RC-26 it's supposed to have.

Patrick

[Dave S.]

Re: '70 BB a/c brass expansion tank ???'s

Patrick,
Those RC-26 caps are getting real scarce, I believe. Is the RC-26 correct for a 70 BB w/ A/C.????

[Patrick H.]

Re: '70 BB a/c brass expansion tank ???'s

Dave,

I believe it should be the RC-15, as it was used on all Corvettes of 1970 with the copper-brass radiator and integral supply tank OR copper-brass supply tank (external).

In a nutshell, RC-26 went with aluminum, RC-15 with copper-brass.

Patrick

[Tony H.]

Re: '70 BB a/c brass expansion tank ???'s

Dave,

Thanks for the kudos on the article.

Yes, Patrick is correct. The material of the rivet in the radiator cap always matches up with the material of the tank of which the cap is applied. So the RC-26 with aluminum rivet goes on aluminum expansion tank or aluminum radiators (if there is no expansion tank). RC-15 with brass rivet goes with brass expansion tanks or copper radiators (if no expansion tank is used). In 1973 and later, when they switched to stainless caps and rivets, this matching material rule-of-thumb goes away.

Tony

By the way, you wouldn't happen to still have your RC-26?

[Patrick H.]

Re: '70 BB a/c brass expansion tank ???'s

"By the way, you wouldn't happen to still have your RC-26?"

Hey! I asked first.

I know Dave no longer has that car, so I would "assume" the cap went with it.

Patrick