Radiator Cap Pressure?

[chucky07]

before i replace my water pump today..i thought..i'd ask what pressure (lb.) cap should I be using..I can't find that anywhere..i even looked in the owners manual in the glove compartment...

I have a 8lb on there now..but i read in the p15 forumn where you use a no pressure cap..

Maybe this is why my temp creeps up there???

thx

[55 Fargo]

Kevin, you have a 1952 rad which is a pressurized type, you should use a 4 lb cap on it, 8 may be a little high, I do have either a 4 or 7 lb cap around here somehwere and there brand new. Or easier yet go to NAPA, Carquest or one of those type of places, take the current rad cap thet fits and get a 4lb cap. But to make sure you don't have some earlier rad, send me a pic of the top of the rad, I will also check the pics you sent me to see if I can verify the type of rad you have.........Fred

[chucky07]

thx got a 4 lb...

[MBF]

I thought all of these flathead sixes except those at the end of the run were non pressurized. I'm running a non pressurizied cap on my 52 1ton and my 36 plymouth. Wouldn't be the first time I've been wrong! Mike

[Bill pilot99]

I found out the hard way, before putting the front clip on I had the ole gal running with a 14 lb. cap on. Blew the radiator top off.

No pressure caps on the ole flat heads, book said only use 4 lb. when doing alot of idling.