Being a non mechanic, after my 63 Dart overheated, I assumed it was because of lack of pressure, since my radiator cap was bouncing all over the place. I went to Napa, and got a new cap, and hoses (since I was adding pressure it obviously didn't have). It concerned me when Napa handed me a 13 pound cap, when I was holding a 7 pound cap. I asked them about it, and they told me 13 pound was what the book called for. Again, being a dummy with these things, I assumed I the 7 pound cap was wrong. As I bought the car this way. Needless to say, this week I spring a leak. The radiator tank split. When I took it to Buck, the local radiator guy, he was stunned to see the 13 pound cap on, and told me I should have a 6 or 7 pound cap. I went back to Napa, and asked them for the part number for the 63 Dart. And again, they came back with a 13 pound cap. They said to get Buck to write up this was an original radiator, and the 13 pound cap was the problem. Yeah right. Buck knows it should be 7 pounds, but is referring me to the dealer. As he is not willing to put that in writing, not knowing for sure if it is the original radiator. I don't know if the dealer will come back with 7 pounds, and be willing to write up that is what it came with. If they can, Napa will pay for the fix. If they can't, I pull out the radiator, and Buck does his thing for $75. All that to ask - anyone else with an old 1963 radiator? If so, what pressure cap do you have?

Non-A/C cars got 14-pound caps from the factory.
A/C cars got 16-pound caps from the factory.

7-pound caps were never factory installed or recommended on these cars, in any year, in any market. Your radiator guy is wrong. The '63 Dart factory service manual proves him wrong, as does the '63 Dart factory parts catalogue.

You just had some bad luck (and a radiator guy who's full of beans), is all. Some people put low-pressure caps on old radiators out of a belief that this is a good idea. It is not. The system is designed to run with around 13 to 16 pounds' pressure. Lower pressure than that permits local boiling with attendant damage risks. Contrary to what guys like Buck think they remember, the right way to do it is to run the correctly-rated pressure cap with a sound and properly-built radiator. Radiators do not last forever; every ten to tweny years they will need a complete overhaul.

If I sound overly forceful or strident here, please understand I am not attacking you. Incorrect information such as your radiator guy gave you is kind of like a campfire. Unless it is stamped out—and stamped out hard—it has a nasty way of hanging around, coming back, and making problems down the line.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks Dan. I knew you weren't coming down hard on me. Buck, however.... With that 7 pound from before, the previous owner probably assumed the lower pressure would help. That makes sense it is 13 pounds, if that is what Napa is giving me. So it sounds like I get that radiator rebuilt. I did happen no notice in the Napa book that 7 pound caps did come with some cars from the mid 50s. He was probably mistaken with them. Once again, you are the MAN!!! And I again will be trusting Napa.

Yep, in the '50s and earlier there were cars that used 7-pound or 4-pound or no-pound radiator caps. But by the time the first slant-6 cars came along, those were ancient history.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Something to remember when you fill your radiator back up.Do not fill it to the top.Fill it to around 1"-2" from the top.Leaves room for expansion.No more puking coolant out your overflow tube when she gets hot.

JZ

I'd fill it to the top and put an overflow tank on it.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

I used a 0-pound cap to make it home once.....................

The seam split on the lower tank.

Gooped it with silicon, left the cap off, filled with water, and limped home.

Lack of pressure kept it from blowing out the silicone.


I can see a 7 pound cap being used as a bandaid on an old radiator...........

Radiator starts to get some pin hole leaks, lower the pressure, no more pin hole leaks develop......

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

That for the big top header tanks. If it's a small top header you need the overflow tank.


(if you fill it up too high, it will eventually stabilize at the right leve......)

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Thanks for all the input. Yeah, I know where the level normally sits, after it heats up and spills out. That is where I will fill it to. As for an overflow tank, I was searching on the net, but never found anything that looked useful for this car. Then again, I am no mechanic, but I am learning, thanks to all of you.

If he has the original 1963 Rad in his car the top is a expansion tank.The level of coolant should be 1"to2" below the top.

Filling to the top and adding a overflow tank will do nothing but give the coolant somewhere to go because it is filled to high.

Now if you are saying fill to the top and add a coolant recovery system,then I would agree.When you do this you will also need a coolant recovery rad cap.

Took my old radiator into good old Buck. I told him you all said it should be 13 pounds. He argued that it should be 7, and showed me where the tank was fixed before, from too much pressure. After looking it over, he said I needed a new core. Of course, I wasn't leaving it for him to work on it. Having said that, I am looking around for another radiator. However, I see some numbers on the top of the tank. It reads 2276826 with what looks like DD over CD with AC to the right of that. Now my Dart doesn't have AC. I am curious. Anyone know what that number is? If it is a model number, does it seem like an original radiator to you?