VCCA Home Forums TECHNICAL - 1945 AND NEWER 1955-1957 Correct Radiator cap

On my 57 Chevy, I have a original seven pound radiator cap. I have been told that putting a ten or eleven pound, Or even higher radiator cap on that It would be better then the seven pound cap I now have on the radiator. Does anyone have any thoughts why this may be a better way to go with the higher pressure cap. :confused:

The higher pound cap will increase the cooling system pressure and raise the temperature at which the coolant will boil.With a 7 pound cap plain water will boil at about 224 degrees at sea level.With a 50/50 antfreeze mixture that boiling point will be raised another 5 degrees or so.The 11 pound cap will raise it another 4 degrees above that.If you are not having a problem now let well enough alone.The increased pressure could blow out you radiator core or heater core if they are old and weak.Neither cap will prevent overheating - and that engine never had an overheating problem when new.

Hey Don,

What did "they" say would be better about a higher pressure cap??

My thought about a higher pressure means any "weakness" in the cooling system is more likely to demonstrate itself.

Frankly, I've done just the opposite - put on a lower pressure cap - in some instances to 'tide me over' til I could address an unknown problem.

My thinking basically "mirrors" Chev Gene's.

And then the best thought of all - "if it ain't broke, don't 'fix' it!!"

What I was told Is that for every pound of higher pressure radiator cap you use, That the boiling point would raise three degrees. I do not have a problem with overheating and have never thought about putting a higher pressure cap on my car. A seven pound cap Is what my car takes. As for a higher pressure cap,This Is just what a couple of know It all car buffs were telling me.

What they are telling you is correct but should not be necessary is your cooling system is in good condition.

I have driven my '57 in 110 degee weather and by the end of the day with the heat pouring off the pavement the temp gauge needle would be right up to the last mark-never boiled and never required adding of coolant.

If you do drive under extreem conditions you could install an 11 lb. cap for traveling-such as for going over mountaain passes ,etc.- would give you a few extra degrees to play with.

Just a warning-In 1958 with the 11 lb. cap they went to the screw type radiator clamps as they would blow off hoses with the wire clamps.

Gene, Wouldn't the screw type clamps be 'points off' for Don at shows?
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Yup-thats why I would live with the 7 lb. cap.

Hey Gator, If your 57 Is stock with the 283 engine In It,As Gene says, Stick with the 7 pound radiator cap. I will, No matter what I have been told about higher pressure caps.

No problems here, keep my 7lb. 283 runs like a dream...

Gene,
When you say screw clamps you mean tower clamps not the "worm gear clamps" correct? You might want to check that I think the tower clamps began in 59, and 58 was still spring ring all around.with the exception of the bypass hose on the 348's. The Robertson Media Archives book supports this with the 58 engine photos shown.
John

I didn't research it but I remember the real early '58 as having the spring clamps.When the hoses began blowing off they changed to the screw type clamps...but don't remember just which type.The new car set up area was right in front of the parts counter where I worked.I remember one accident where the new car get ready guy was burnt when it sprayed him with (hot) anti-freeze.