68ragtop

While I had my radiator in the shop the guy asked why I had a 16 lb cap on it. I really didn't know what to say except that it was on the car when I got it. He said to run a 7 pounder but didn't elaborate why. What's the pro's and cons to higher or lower pound caps?

I'm running a 400HP 350, 4 speed with a 4 core radiator. Higher volume water pump with a 160 degree stat, no air.


[Modified by 68ragtop, 1:14 AM 3/30/2004]

PRNDL

I think stock was 15lb. All I can see accomplishing with a 7lb cap would be to have your overflow spritzing out coolant on a hot day unnecessarily.. :confused: but that's just my guess..... MJ

Bullyj

I think stock is 14 or 15. I don't know why anyone would run a 7 Unless you live in a cold climate.

73 Vet

The good folks at DeWitts recomended 15# to me.

Brown78

Bought and drove my 78 L82 from Providence, R.I. to Ft. Lauderdale. ran great until I got to south FLA. Couldn't figure out why everytime I stopped the coolant would blow out the overflow. A friend told me to check the radiator cap. Seven lbs. You definitely need a 15 or 16 lbs cap. Get the one with the pressure release arm on the top of cap :seeya Steve P.S. Now, I'm running just about the same drive train as you. :thumbs:


[Modified by Brown78, 2:26 AM 3/30/2004]

78 Vette

:iagree:

Super Stock

Was this guy a racer or anything ? Some race cars with a lot of porting to the point of almost getting into the h2o jackets will run low pressure to try not to overpressure and blow out into the intake runner. I like that 15# you were talking about for the street.

71'AirStrike

rasing the poundage on the rad cap increases the pressure the system can hold. The higher the sytem pressure the higher the temp at witch boiling occures in the rad fluid.

when you get boiling .. you get puking :U

vetts need 15#

I think mine is 17 to 20. but I live in arizona

cheers
chad