What is Correct Piston for 1954 with 327 cid Engine?

Posted by Steve Davis On 2011/3/15 19:40:38

I was hoping someone on the forum could confirm what is the correct piston for a 1954 Packard Clipper with 327 cid engine. It is a 5401-5411 series.

Max Merritt states that the slot into which the top compression ring goes should measure from top to bottom at 3/32, for the middle ring, also compression, should measure 1/8 and the slot for oil ring measure 3/16. The pistons on my Packard the top ring is 1/8 and the middle ring 3/32 and oil ring 3/16. The pistons in my Packard all have the number 403535.

I have also measured the slots for the rings on my pistons using an inside digital caliper. Measurements are: top ring 0.108, middle ring 0.097 and oil ring .1860. The 1954 Packard shop manual states that the rings themselves, both compression rings are the same at .093 and oil ring .1860.

Another mystery is that even though the car has 60,400 documented miles it appears one or more of the pistons have been replaced.

The previous owner had replaced the head gasket yet foolishly didn't remove any carbon from the top of the cylinders and didn't even change the oil after the repair. Then with two stuck valves they allowed the car to sit for a couple of years. One cylinder/piston adjacent to the stuck valves had rusty sludge on it. That one piston is an Autothermic brand as specified in the shop manual. It was very pitted on top and the rings were rusty and deteriorated. The other 7 pistons are Permite brand and are in excellent condition. Both the 1 Autothermic and 7 Permite have the number 403535 and the slot for the top ring is the same at 1/8 and middle ring at 3/32.

I hate to throw out 7 flawless pistons and buy 8 pistons from Max Merritt so that they all have a top ring slot at 3/32 and middle ring at 1/8. Max was emphatic that my pistons are "not a Packard piston." Even if I stay with the 7 Permite pistons I still am going to need a replacement for the bad Autothermic and it will have to have a top ring slot at 1/8 and middle ring at 3/32 to conform.

I'm sorry this was so long-winded but I wanted to share all the facts. I really appreciate any advice you gentlemen can provide.

---Steve