Packard Forum Index » Post-War (1946-54)

Most kind of you to post thanks and comments on everyone's contributions. This old car stuff is often a puzzle and that's some of the fun of it.

On your conclusion to find pistons that match the shop manual specs. Packard and other companies constantly made improvements in vehicle engineering and then incorporated the changes into replacement parts. With pistons the ring groove combinations were changed as ring technology improved to give longer ring and piston life. In general the top two rings got thinner with better metallurgy and had less friction losses and longer life while maintaining sealing properties.

3 1/2" pistons were used from the '38-50 Six and the '40 356" thru the '54 288/327 and they all interchange although there are many part numbers. Any set of 8 matched pistons will work in your engine. If a part is described in the parts book as "assembly" as the piston is, that usually means it consists of more than one individual piece. The part# cast into the piston is the part # of the piston with a standard pin. The number is for internal use only. The pin is the second part of the assembly I presume. Often the assembly part # is 1 digit higher than the casting #.