13 lb. Radiator Cap

[cbillelder]

Just looking for some opinions here.
I'm running an 8BA flathead with a Walker radiator in my '32 hot rod. I know the radiator can take the pressure, but will a freshly rebuilt pair of original 8RT water pumps be okay with 13 psi, or should I go back to the 7 lb. cap??
Thanks for your input!
Bill

 

[Krylon32]

I'd stay with the 7 lb cap. I think the new pumps with ceramic seals and roller brgs can take the higher pressure but the originals seem to marginal at the higher pressure. Sometimes it works fine and sometimes it doesn't

 

[joe plumber]

I had a 13 pound cap on my radiator, worked with no problem.

 

[Pete]

If it cools and doesn't puke water, you shouldn't need the 13lb one.

 

[G.M.]

Higher pressure in the system pushes the seal tighter against the seat so leaking is no a problem. Safety and damage to parts can come from high pressure. You should not need more than a 4 lb cap if the temperature don't get over 205. If it pucks water below 205 the pressure cap isn't seating down in the bottom of the neck or you have a compression leak putting pressure in the cooling system. The main purpose of a pressure cap on old STOCK Fords is to keep the water from going out the overflow, not to pressurize the system and it acts as a safety valve to release pressure in case of a problem. G.M.