1964 Radiator Cap

[Patrick C.]

The radiator cap below was on my 1964 FI Convertible when I bought it. Is it a repop or original? If original how will it do in judging?

[Richard G.]

Re: 1964 Radiator Cap

Pat;
I can't say for sure but it doesn't look at all like a reproduction.

Corvette Expansion Tank Cap, Small Block, 1963Late-1967 (Reproduction pictured below)



Below is a picture of the original cap for a December 1962 car.



Looks like you have the original cap. At least if they didn't change them from the 1963 model.
I might add that it appears to be in excellent physical shape.

I need to get mine rebuilt. As it failed to pressurize. I have had it re-plated, as shown in the picture.
Any recommendation on where to send it?
Rick

[Timothy B.]

Re: 1964 Radiator Cap

Patrick,

The cap looks original to my eyes but others may know how to spot the repro better than me. Flip it over and snap/post a picture, that will probably tell for sure.

A long time age I bought a reproduction cap for my 63 and it did not relieve pressure until approx 17lbs. Most reproduction stuff is junk IMO, if the cap is repro go find a genuine AC service cap RC-26 but find one that is stamped AC because it's made in the USA not the foreign made TVS stamped cap.

[Joe L.]

Re: 1964 Radiator Cap

The radiator cap below was on my 1964 FI Convertible when I bought it. Is it a repop or original? If original how will it do in judging?

Pat------


I think this is an original cap or, possibly, an old GM SERVICE cap. There's really no way to discern a cap originally installed on the car and a GM SERVICE cap identical to the original.

The thing that I find curious is the rivet and the reddish residue surrounding the rivet. The rivet appears newer than the cap and not quite the configuration I'd expect. So, it may be that this cap has an original shell but has been rebuilt by having the underside "guts" replaced.

I can't explain the reddish residue, though, unless you are using some sort of red dyed coolant and there is a slight leakage around the rivet. The latter condition would be further evidence that the rivet has been replaced as part of a rebuild. I've never seen an original GM cap leak at the rivet.

[Alan D.]

Re: 1964 Radiator Cap

Here is an original from a Mar64 FI car. Notice the faint start of the circle around the 307/13# It appears that on later caps the circle became more noticeable.

[Patrick C.]

Re: 1964 Radiator Cap

Pat------


I think this is an original cap or, possibly, an old GM SERVICE cap. There's really no way to discern a cap originally installed on the car and a GM SERVICE cap identical to the original.

The thing that I find curious is the rivet and the reddish residue surrounding the rivet. The rivet appears newer than the cap and not quite the configuration I'd expect. So, it may be that this cap has an original shell but has been rebuilt by having the underside "guts" replaced.

I can't explain the reddish residue, though, unless you are using some sort of red dyed coolant and there is a slight leakage around the rivet. The latter condition would be further evidence that the rivet has been replaced as part of a rebuild. I've never seen an original GM cap leak at the rivet.

Thanks Joe,

Interesting, I have no idea what the red stuff is? I will take the cap off today and see if I can figure it out and clean it up. The coolant I put in it last year was not red so it would have to have happened earlier. This car had been setting since 1983 so I am not sure what could have happened.
I will take some pictures today of the other side of the cap and post them tonight.

[Patrick C.]

Re: 1964 Radiator Cap

Here is an original from a Mar64 FI car. Notice the faint start of the circle around the 307/13# It appears that on later caps the circle became more noticeable.

Thanks Alan,

My car was a late January 1964 build date. I dont see any traces in my picture of the die marks your cap shows. I will take a closer look today and post some pictures of the other side.

[Patrick C.]

Re: 1964 Radiator Cap

Patrick,

The cap looks original to my eyes but others may know how to spot the repro better than me. Flip it over and snap/post a picture, that will probably tell for sure.

A long time age I bought a reproduction cap for my 63 and it did not relieve pressure until approx 17lbs. Most reproduction stuff is junk IMO, if the cap is repro go find a genuine AC service cap RC-26 but find one that is stamped AC because it's made in the USA not the foreign made TVS stamped cap.

Thank you Timothy, I will take some more pictures today and post them.

[Patrick C.]

Re: 1964 Radiator Cap

Pat;
I can't say for sure but it doesn't look at all like a reproduction.

Corvette Expansion Tank Cap, Small Block, 1963Late-1967 (Reproduction pictured below)



Below is a picture of the original cap for a December 1962 car.



Looks like you have the original cap. At least if they didn't change them from the 1963 model.
I might add that it appears to be in excellent physical shape.

I need to get mine rebuilt. As it failed to pressurize. I have had it re-plated, as shown in the picture.
Any recommendation on where to send it?
Rick

Richard

Did you take it apart to have it replated?

[Michael J.]

Re: 1964 Radiator Cap

The TIM&JG states the cars built from August 1963 throughout the 1964 MY had a circle around the 307 13# stamp.

[Joe L.]

Re: 1964 Radiator Cap

Here is an original from a Mar64 FI car. Notice the faint start of the circle around the 307/13# It appears that on later caps the circle became more noticeable.

Alan------

Features like you mention can easily vary from cap-to-cap. Different sets of tooling which may vary slightly and/or tooling wear over time can easily account for these differences. These basic caps (of course, not all '307's') were being manufactured by the millions and used across all GM car and truck lines. I'm not even sure that all of the embossing on the caps was being done in the same stamping operation (e.g. the cap model may have been stamped separately from the rest of the embossment).

[Dan H.]

Re: 1964 Radiator Cap

Alan's is the only original that I've seen with a trace of a circle, all the other 307s I've seen haven't had this feature, manual should be amended due to recognize obvious variations in 307 caps.
Dan

[Patrick C.]

Re: 1964 Radiator Cap

Thanks Gentlemen,

I went back and reviewed the TIM&JG. Michaels is correct so it looks like I have the wrong cap according to the book. I do believe this was the original cap but no way to prove it. Good news is that I have a rare and valuable ‘63 cap and not a lowly low buck ‘64 cap! Pictures of the other side below along with a close up of the top where the circle was suppose to be. It shows some red corosion on the spring but I have green tint antifreeze so this is a remnant of the past.

Is this a complete deduct in judging?

[Don H.]

Re: 1964 Radiator Cap

Patrick, it's a real cap, and very well could be original to your car. You really need to get involved in judging as an OJ, or a judge, or as owner to learn how judging works. It is just about impossible to learn how it works through Q&A on the TDB. No, it cannot be a full deduct. It is a correct AC cap, correct for your car in every way except perhaps for minute markings. I believe the markings are correct for your car, as they are for my Jan 64 car, (and my 65 L76). Despite what the JG says.

[Patrick C.]

Re: 1964 Radiator Cap

Patrick, it's a real cap, and very well could be original to your car. You really need to get involved in judging as an OJ, or a judge, or as owner to learn how judging works. It is just about impossible to learn how it works through Q&A on the TDB. No, it cannot be a full deduct. It is a correct AC cap, correct for your car in every way except perhaps for minute markings. I believe the markings are correct for your car, as they are for my Jan 64 car, (and my 65 L76). Despite what the JG says.

Thanks Don,

Good advice. I will find some time to get more educated on the process. Just rushing to get this thing ready for judging this spring. Lots to do.