Is there a specific reason you don't want the 4 lb cap?

Are you worried that your system won't be able to handle the pressure?

My truck has an unmodified 1941 radiator and a vintage heater. It has a 4 lb cap on it and it has never caused any problems. The engine rarely exceeds 180 degrees so there isn't even the likelihood that the engine will ever reach the 224 degree level.

I think the 4 lb cap will work just fine. I also think the 0 lb cap for a 1952 would work as well. Was there some major design change to the radiator filler tube in '54 where the earlier caps won't fit?

1950 Chevrolet 3100 (Ol' Roy)

1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)