Radiator cap for 66 327

[Randy S.]

Gentlemen,

I have an incorrect RC 15 15# radiator cap on my 66 300HP 327 with C-60. I don't have the car judged and someone pointed out that my cap should be an RC 26 15#

Is there an issue with galvanic corrosion with the incorrect RC 15 on a car with aluminum overfow tank and radiator? I understand the RC 26 was strictly a corvette cap so I am thinking there must be a reason for 2 similar 15 # caps.

Randy

[Joe L.]

Re: Radiator cap for 66 327

Gentlemen,

I have an incorrect RC 15 15# radiator cap on my 66 300HP 327 with C-60. I don't have the car judged and someone pointed out that my cap should be an RC 26 15#

Is there an issue with galvanic corrosion with the incorrect RC 15 on a car with aluminum overfow tank and radiator? I understand the RC 26 was strictly a corvette cap so I am thinking there must be a reason for 2 similar 15 # caps.

Randy

Randy-----


The RC-26 was specially designed for use with aluminum supply tanks and aluminum radiators. It included an aluminum rivet and a special insulator to isolate the steel shell of the cap from the aluminum neck on which it seated. All of this was done to minimize the effect of dissimilar (galvanic) corrosion.

Using an RC-15 cap is not going to result in the immediate or even long term failure of your tank or radiator. However, I think it would be prudent to replace the cap with an RC-26. The RC-26 is still available from GM and Delco although it's external configuration differs markedly from the originals (hexagon shaped shell, etc.). Reproductions of the RC-26 are also available. They do use the aluminum rivet but I don't know that they include the other insulating features of the original RC-26 (i.e. they're more concerned with nuances of EXTERNAL configuration than they are with functionality)