C2 RC-26 radiator cap

[Joe R.]

My 67 small block has an old RC-26 radiator cap, and I am trying to determine whether it is original. I have read the achives on these caps and I understand that the design sold as a SERVICE part evolved over the years.

My cap has big ears and a steel top, so the basics are covered. However, it does not quite match the drawing in Chuck Brigermann's "Essentials" book, nor the reproduction shown in the Paragon catalog.

The main difference is that on my cap, the "15#" and "RC-26" stampings are all the way out on the ear, and the bottom of the text faces the center rivet. On the Paragon reproduction and in the "Essentials" book, these two stampings are much further inboard (symmetric with the AC logo) and the text is rotated 90 degrees from mine.

Recently a restored cap that exactly matches mine sold on ebay. There are some nice photos of the top in the listing (item 4539201442). Evidently *someone* thought that cap was correct (at least for some years), because it sold for $346 !!!

By the way, does anyone know of a restoration service for radiator caps? If mine turns out to be original, I will want to have the top replated.

[Gary B.]

Joe; John Pirkle restores these caps. *NM*

[Tony H.]

Re: C2 RC-26 radiator cap

Joe,

I believe your cap may be an original cap, whether it is original to your car or not I cannot say for sure. The original caps were as you describe only the steel top was definitely zinc plated according to some of my research. In the next few months, Patrick Hulst and I will be writing several articles for the NCRS Restorer Magazine regarding the radiator caps of this era. We plan to start with the RC-15 cap followed by the RC-26. There are some variations to the caps observed on original cars as well as service replacements. The service replacements observations show much more dramatic changes like materials of construction (stainless steel vs zinc-plated steel cover, etc.).

I would recommend holding on to the cap at least until the articles come out so you can be more informed. We plan to present our research including cap photos, timelines, materials of construction of original, service replacements, and various levels of reproduction caps. Presently, no one to my knowledge makes reproductions of the RC-26 as configured in the 1966 to 1972 timespan.

[Wayne M.]

RC-26 Feel my Pain

I'd agree with Tony that there were many variations. My early '65 C60 has a cap that is best approximated by the re-pop catalog's description of the 63E and '65-L78 cap, EXCEPT that instead of AC (then under) 307 with an underline (then again under) 13#, I have AC (then under) 15# (no underline, then again under) RC-26. Base of all above points towards center of cap; nothing out on the ear.

It's still in the same grungy condition as when I bought the car in 1980; (ie: no guarantee that it's factory original, but the car DOES have its original horns and shocks). I should email a pic to Tony and Patrick.

[Kent K.]

Re: C2 RC-26 radiator cap

You have email.
Kent

[Patrick H.]

Send the photo! *NM*