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

I’m looking to purchase a 1954 Packard Convertible, which is supposed to have a 359 in it. The head has 327 stamped on it. Are the heads of the two engines interchangeable or is it more likely that the engine has been replaced? Thanks in advance for any help!

Should be able to get the casting numbers of the block and head and compare on this site to what should be in there on parts list, etc. sans a build sheet tucked away some where.

The heads are interchangeable and many aluminum heads were replaced by cast iron when the aluminum corroded or was otherwise damaged. There is a need to use the correct cast iron head from specific years. The wrong one can increase the already high 359 compression ratio to an almost undriveable ratio where no hi octane gas or distributor setting will get rid of the ping. If the car is driving and sounding good then the head should be one of the proper ones.

To check if the entire engine has been replaced look at the motor number stamped on a smoothed pad on the block a few inches above the starter. The 54 359 block will start M6xxxxx. Any other letter is a different year and any second digit other than 6 in conjunction with the M is a smaller engine.

The engine number itself will tell you which one it is and can be found on a raised boss under the edge of the head on the driver side near the back above the starter. I always have a hard time finding it but there is a chart on this site that will tell you which engine it is based on that number.

As for the question, yes, the cast iron head will fit but it is thinner so unless the studs were shortened, they may stick out a bit too far. Also, using the 327 head on the 359 will change the compression ratio.

This is the chart that shows what fits and what compression ratio results:

288/327/356/359 head interchange chart