Radiator Cap

[W K.]

Looking for some help. The 1966 Judging Guide states that "small block expansion tanks use an AC model RC-26 cap." The part houses are listing an AC 307, with a #13 for non A/C. My owners manual says it is equipped with a 15# cap, which is consistent with the Judging Guide. I already have the wrong one and I don't want to purchase the incorrect one again.

Thanks for your help!

[Ronald L.]

Re: Radiator Cap

I think you are going to find that the reproduction parts are not correctly configured, for sure that is the case for the BB cap.

[W K.]

Re: Radiator Cap

I have seen that on other items as well, just double checking.

[Ronald L.]

Re: Radiator Cap

One of the frequent guys here is an expert in the subtle differences, might even find some of that detail by searching the forum archives.

[Peter L.]

Re: Radiator Cap

Patrick - Originally your sb '66 would have had an AC RC-26/15# radiator pressure cap installed on the aluminum overflow tank. The AC 307/13# radiator pressure cap was used on sb Corvettes with aluminum overflow tanks thru 1965 Production. If you are looking for an original RC-26, please note that the covers on the original caps were zinc plated steel and not the stainless steel cover AC RC-26s that were available until recently. Pete

[Joe L.]

Re: Radiator Cap

Patrick - Originally your sb '66 would have had an AC RC-26/15# radiator pressure cap installed on the aluminum overflow tank. The AC 307/13# radiator pressure cap was used on sb Corvettes with aluminum overflow tanks thru 1965 Production. If you are looking for an original RC-26, please note that the covers on the original caps were zinc plated steel and not the stainless steel cover AC RC-26s that were available until recently. Pete

Pete------


I believe the RC26 is still available. However, it's configuration is NOTHING like the original. It should be 100% functional, though. The RC26 also replaced the RC15 for SERVICE.

[W K.]

Re: Radiator Cap

Thanks, the RC-26 are available and part house show them as the correct replacement. The others that I looked at show the other incorrect cap.

[W K.]

Re: Radiator Cap

Correction, 2 part houses show them as correct.

Thanks again for all of your help. That is the kind of information I needed.

[Joe L.]

Re: Radiator Cap

Correction, 2 part houses show them as correct.

Thanks again for all of your help. That is the kind of information I needed.

Patrick------


The RC-26 currently available is correct but only FUNCTIONALLY correct. It is definitely NOT CONFIGURATIONALLY correct.

[Patrick H.]

Re: Radiator Cap

Patrick------


The RC-26 currently available is correct but only FUNCTIONALLY correct. It is definitely NOT CONFIGURATIONALLY correct.

At least one of the repros is not entirely configurationally correct as well.

[Ara G.]

Re: Radiator Cap

Patrick,
I have 2 original RC 26 caps. If you want some pics I would be happy to email them to you. I would post pics of them on the DB but I still haven't mastered how to post pics on the DB. I have read that originals could have the the stamping on the right side of the cap BOTH vertically as well as horizontally. Ironically, I have one of each....Let me know...They are TOUGH to find originals....Regards......ARA

[Peter L.]

Re: AC RC-26 Radiator Cap Stampings

Ara - On the RC-26 radiator pressure caps used starting with 1966 Corvettes with aluminum overflow tanks, the most typical stamping of the 15# & RC-26 is on the right hand "ear" of the cover and either vertical or horizontal as you have observed on the your caps. These also have the stamping with the AC in a circle over by the left "ear" but more towards the center of the cover.

There are some addition stamping configurations that I have observed on RC-26 caps over the years and they are as follows:
a) a vertical stamping of the 15# & RC-26 on the left "ear" and the stamping of the AC in a double circle over by the right "ear" but more towards the center of the cover.
b) a vertical stamping of the 15# & RC-26 on the left "ear" and the stamping of the AC in a circle also over by the left "ear" but more towards the center of the cover. This cap was on my base motor '67 when we bought it in 1983 and still is.

While I have only seen 2 examples of "a" above with the double circle around the AC and 1 of the configuration with both the stamping on one side of the center, I'm sure there are more out there and probably more different stamping configurations, like maybe "a" above with a horizontal stamping of the 15# & RC-26. So far assigning a date to a specific stamping configuration is questionable because of limited data points and also because many RC-26s were replaced because the large aluminum washer under the cover eroded away and/or the cap failed to hold pressure.

The good news is if you find an older RC-26 it is a Corvette radiator pressure cap.

BTW, it should be noted that the above is directed to RC-26s used on 1966 and newer Corvettes. Pre-1966 Corvettes, i.e., 1963-1965, with C-60 air conditioning also used a 15# RC-26 cap but the stamping configuration on the cover is different and similar to the 13# 307 caps used on 1965 Corvettes and older.

Pete

[Wayne M.]

Re: AC RC-26 Radiator Cap Stampings

...BTW, it should be noted that the above is directed to RC-26s used on 1966 and newer Corvettes. Pre-1966 Corvettes, i.e., 1963-1965, with C-60 air conditioning also used a 15# RC-26 cap but the stamping configuration on the cover is different and similar to the 13# 307 caps used on 1965 Corvettes and older. ...

Pete --- whew ! you had me worried there for a minute [re my early '65]

[John M.]

Re: Radiator Cap

Patrick,
Check out Dewitts. They have a nice reproduction. Not sureexactly how close it is to original but they look good

[Peter L.]

Re: Radiator Cap

Wayne - I though you might be in hibernation so I post on the DB every once and awhile to see if you are out and about and reading the DB postings. Does your '65 have air conditioning???????? If so when do you use it???????? Oh now I remember when, a friend on mine in Houston who had been up there, said they did a number of things on the one day of Summer like have a picnic or go hiking, so I guess that's when you use the AC. Pete