RC-26 Radiator Supply Tank Cap

[David L.]

Re: RC-26 Radiator Supply Tank Cap

Dave - I didn't study your photos initially, but after looking at the cap I the right I'm curious about the 15#/RC-26 stamping being just to the right of the center depression and not on the ear. Does this cap have the typical AC radiator pressure cap lower seal and valve? Pete

Pete,

Enclosed are 3 photos (using my wife's camera which I am not that familiar with) of the cap that I believe to came from an early 1969 Corvette. The seal is a fiber type.

Dave

[David L.]

Re: RC-26 Radiator Supply Tank Cap

Dave -- these two pics might be the ones of the type that you're refering to in your blueprint, from the pre-'66 era.

n

Exactly.
Thanks for the photos.
Dave

[Peter L.]

Re: RC-26 Radiator Supply Tank Cap

Dave - The photos look good. The lower seal and valve are typical of the original 15#/RC-26s I have seen and the large aluminum washer directly under the cover looks to be in good condition. This cover stamping is the first one of this configuration I have seen. It looks like a combination of the cap design that started with the 1966 Production year because the center depression is larger in diameter than what is found on the 1963-1965 RC-26s and it has the AC logo in a circle which started in 1966 but the 15#/RC-26 stamping is close to the center depression like on the 1963-1965 RC-26s rather than out on the ear which is typical of what we see on the 1966 design. It's always interesting what new things come up. Neat find.

BTW, thank your wife for letting you used her camera.

Pete

[Jeff C.]

Re: RC-26 Radiator Supply Tank Cap

I have five original RC-26 caps, including one that was NOS until I put it on my '67. Will take a look at them. Joe Perri from Chicago area rebuilds the RC-26 caps and does a super job... I believe he uses doner internals from the replacement stainless GM RC26 caps, but has fabricated the correct aluminum rivet and has them replated nicely. He tests them before sending back and since they have the original GM style parts, you should not have the risk I've heard where part of the internals gets sucked into the radiator (on the repro caps). Joe noted that he has seen four different variations on the RC-26 cap - not sure which is later or earlier... Joe's contact information is: 312.307.1977 and email is corvetteillinois@comcast.net. Will take a few pictures this weekend. Regards, Jeff Cornwell

[David L.]

Re: RC-26 Radiator Supply Tank Cap

Yesterday at a swap meet in Mansfield, MA, I found an "early" 1967 3155416 supply tank dated "66K" (Oct. 1966) with a 15# RC-26 AC cap. As shown in my photos the "15#" and "RC-26" stampings are on the left "ear" in a vertical position. The encircled "AC" is on the right side. I really believe that the cap is original to the tank. I cleaned the cap with an SOS pad and some NEVER DULL. The tank is in poor condition. The gasket can be removed in one piece if you soak it in water for a while as it can be quite brittle being about 46 years old.

Dave

[Peter L.]

Re: RC-26 Radiator Supply Tank Cap

Dave - GR8 find. The locations of the stampings on the cover of the RC-26 Radiator Pressure Cap you found are consistent with the RC-26s with the double circles around the AC logo. As has been mentioned before, there have been at least 4 if not 5 different cover stamping configurations observed on RC-26s. Personally, I find it interesting that there were that many cover stamping configurations on a relatively limited usage cap from both a Production & Service part perspective. I guess it just another one of those things to keep those NCRS Judges on their toes. Pete

[David L.]

Re: RC-26 Radiator Supply Tank Cap

Pete,

I'm quite confident that the cap that I just found yesterday was originally from a 1967 Corvette probably made about November 1966. Jerry's cap from his June 1967 Corvette is almost a mirror image of my cap except his cap has the "15#" and "RC-26" stamped horizontally. I know that you mentioned previously that there were 4 or 5 different versions of the RC-26 cap and it appears that there were different versions made even during the same model year.

Dave

[R N.]

Re: RC-26 Radiator Supply Tank Cap

Hi Dave,

My '67 with VIN 5818 built Dec. 12th 1966 has the original surge tank and radiator both dated 66 K, the cap is original to the car too and is the same RC 26 cap as per the posted picture. When I sent it to Joe Perri to be restored a year or so ago, he stated to me that that caps with the RC 26 and 15# on the left ear were not so common.

[Peter L.]

Re: RC-26 Radiator Supply Tank Cap

Kurt - Does your RC-26 have the double circles around the AC logo. If so, those that I have seen have the 15#/RC-26 stamping on the left ear & I agree with Joe, they are not as common as the configurations with the 15#/RC-26 stamping on the right ear. Pete

[R N.]

Re: RC-26 Radiator Supply Tank Cap

Kurt - Does your RC-26 have the double circles around the AC logo. If so, those that I have seen have the 15#/RC-26 stamping on the left ear & I agree with Joe, they are not as common as the configurations with the 15#/RC-26 stamping on the right ear. Pete

Hi Pete,

YES my cap has the double circles around the "AC". See the before and after restoration (Joe Perri) photos attached. Take care.

DSCN6078.jpgIMG_0079.jpg

[Neal K.]

Re: RC-26 Radiator Supply Tank Cap

The above pictures are of the expansion tank radiator cap that cam off of my 67 L79 vin 179. Sept 66. I had put it in a box years ago when a replaced it with a new cap and came upon it today when rummaging thru some old boxes of parts. Can any of you learned folks tell me what I have and whether it was original to my car. Thanks
Neal

[Neal K.]

Re: RC-26 Radiator Supply Tank Cap

I apologize for reposting my question from yesterday but I believe someone knows what year my expansion tank cap goes to(pictured in my previous post). A response is most appreciated.
Neal

[Gerard F.]

Re: RC-26 Radiator Supply Tank Cap

Neal,

I don't think anyone is going to venture a guess as there are so many variations of the RC-26 expansion tank cap. With the "Made in USA" and "PAT'D" it seems to me to be an earlier than 67 cap.

My original late 67 cap shown above is different and fits the mold of later year caps without the language above.

But for an early 67, you never can tell, it may be original to the car.

[Neal K.]

Re: RC-26 Radiator Supply Tank Cap

Neal,

I don't think anyone is going to venture a guess as there are so many variations of the RC-26 expansion tank cap. With the "Made in USA" and "PAT'D" it seems to me to be an earlier than 67 cap.

My original late 67 cap shown above is different and fits the mold of later year caps without the language above.

But for an early 67, you never can tell, it may be original to the car.

Jerry, thanks for your reply. I am inclined to have the cap restored and re-install it on my car.

[Gerard F.]

Re: RC-26 Radiator Supply Tank Cap

Neal,

I would just try to clean it up. I do zinc plating but was afraid to plate mine for fear of ruining the aluminum rivet and operation.
I did apply some zinc spray paint to the top. It is still on my 67 and works fine.