1963 AC 307 13# Radiator Cap vs. Repro

[Joe R.]

Re: 1963 AC 307 13# Radiator Cap vs. Repro

Is there an echo in here?????? Or is it really Easter again????????

Yes, JD I lie awake at night worrying about someone breaking into my house and stealing my 307 radiator cap. The pawn shops around here are just full of original 307 radiator caps. Yeah, right!

Looking at the original picture it looks as if the original cap has been restored as the back is glass beaded and the aluminum rivet has been replaced. Looks like a Pirkle restoration to me!!! Correct observation or not???

JR

[Doug L.]

Re: 1964 AC 307 13# Radiator Cap vs. Repro

I'm picking up this thread again in hope someone can comment on '64 caps. My JG says the AC 307 13# has no circle on the '63 cap but does have a circle around that data on the '64 cap. My original cap is long gone so I have to get something.

The LIC cap has no circle. The ZIP cap has no circle. The Paragon cap has AC in one circle and 307 / 13# in another circle on the opposite sides of the cap.

I'm certain there are many significant differences in the '64 repro vs the original cap, just as there are in the '63 caps discussed above. Given I have to buy something, is the Paragon replacement close to the original, with at least the correct format?

Thanks in advance,
Doug

[Alan D.]

Re: 1964 AC 307 13# Radiator Cap vs. Repro

Remember you are dealing with a corvette, so the answer will be perhaps.

Here is an original Mar64 cap. Notice the slight circle! If you saw the cap in person you would not notice the circle, I only discovered after I enlarge the photo.
My theory is that the stamp tool for 307/13# started to ware hence the beginning of the circle.

[Doug L.]

Re: 1963 AC 307 13# Radiator Cap vs. Repro

Hi Alan,
Thanks for the reply and especially the photo. The Paragon cap is nowhere near correct. The LIC cap has the correct format except for the circle around the 307 and 13#. They say it is for 63-65 which I don't think is correct. From my JG I understand that this design is close to what the '63 cap should look like but the '64 cap had the circle added.
The ZIP cap is very similar to the LIC cap (no circle) and they advertise it as being correct for 61-65.

Guess I'll keep looking now that I know what to look for.

Thanks again,
Doug

[Peter L.]

Re: 1963 AC 307 13# Radiator Cap vs. Repro

Doug - Alan's photo of his 64 AC 307 radiator pressure cap is a nice example showing some of a "circle" impression which I believe and as he mentioned is most likely the outline of the stamping tool because it certainly does not appear to be a design feature as there are other AC radiator pressure caps, like the newer RC-15s, that have circles around some of the stampings and the circles around the AC and the 15# RC-15 are definitely a "design" feature and very distinct.

In addition I have seen numerous examples of "original" AC 307/13# radiator pressure caps and the "circle" impression by the 307/13# stamping ranges from noticeable and mostly complete to faint and incomplete to not evident.

So, if you need to find an original one with some evidence of the stamping tool outline around the 307/13# stamping, it will be a challenge but they do exist; but I don't believe there is a "repop" with that feature. Good luck.

Pete

[Harry S.]

Re: 1963 AC 307 13# Radiator Cap vs. Repro

I just looked at my original cap from my April 63 car. There is no circle.

[Michael G.]

Re: 1963 AC 307 13# Radiator Cap vs. Repro

No circle on my original Nov,62 cap.

[Wayne M.]

Re: 1963 AC 307 13# Radiator Cap vs. Repro

...... But there is one major difference. The repros have been known to stick and then the top radiator hose blows off and then antifreeze does a number on the FI's for sure.

Thanks, Doug L., for reviving this post. Two months ago I did a fleabay buy-it-now on an AC 13# 307. Poor picture but from what I could make out, sure looked like my orignal, shown in post # 6. Described as original used, for 58-62 Corvette !!! Well, it turned out looking exactly like the repro in Jim B's pics. Turns out I could have gotten a brand new repop for the same price I paid. With shipping, is not worth returning.

John DeG's mention of pressure problems made me check my eBay unit. On bathroom scales, pushing down until spring 'gives', I get 21lb with the repop but only 16lb with my original. Also, this repop has no fiber gasket - is it supposed to ?

..... Buy a repro anyhow and keep it in the car though. Good for swapping if you car is on display some where. ....

For the above reasons, I'd be afraid to run my car with this thing on .

[Peter L.]

Re: 1963 AC 307 13# Radiator Cap vs. Repro

Wayne - The original AC 307s had the fiber gasket as did the RC-26s. As far as I know, all the radiator pressure caps used on the aluminum overflow tanks had the fiber gasket.

While the "repop" radiator pressure caps might work OK is some case although the pressure ratings of those caps are quite variable, usually on the high side. Also, I have heard of cases where the caps have come apart and the pieces have gotten into the cooling system. And that will ruin your day.

Pete

[Peter L.]

Re: 1963 AC 307 13# Radiator Cap vs. Repro

Bill - While the 307 pressure caps might be "cadmium" plated, the 66 & 67 Corvette owner's booklets indicate " a 15 lb. zinc plated steel pressure cap," which would be the RC-26 and RC-15. Pete

[Alan D.]

Re: 1963 AC 307 13# Radiator Cap vs. Repro

Wayne, my picture shows an original gasket.

[Harry S.]

Re: 1963 AC 307 13# Radiator Cap vs. Repro

Good information, but NOS originals are really hard to find. Who makes the best reproduction cap, from a judging standpoint?

I have my original, but it is pitted and a bit ugly.

[Timothy B.]

Re: 1963 AC 307 13# Radiator Cap vs. Repro

Harry,

IMO, none of the repro caps look like the original 307. I would keep a eye for a nice used original and replace the fiber gasket and the sealing (smaller ) gasket and the cap will function like new.

I tested the repro 307 I purchased and it popped at 19lbs. The original tested at exactly 13 lbs just as you would expect.

[Mike L.]

Re: 1963 AC 307 13# Radiator Cap vs. Repro

No circle on my #2405, 1964 car