rad cap Y block

[cvicky]

how many lbs rad cap is suggested for 55 272 my manual just says engine runs at 7 1\2 lbs my rad cap says 13 lbs but a seal is missing

 

[dmsfrr]

You need a new functional cap, with a lower pressure rating.
With any luck you can find one similar to this at a local auto parts store.

https://www.ebay.com/itm/Gates-Radiator-Cap-for-1957-1965-Ford-F-100-5-8L-4-4L-4-8L-V8-3-6L-4-9L-3-9L-sx/293348802423?fits=Year%3A1957%7CMake%3AFord&hash=item444cf37f77:g:5CMAAOSwYSFd3M3C

 

[54vicky]

you answered your own question the manual stated proper one why question it?

 

[rotorwrench]

While the old radiators could likely take a 14 lb cap, they aren't getting any younger and they were designed for the 7lb cap.