John,

Thanks for the heads up. I haven't been as regular around here for a while, and I did miss that post. It's rotten how much of that forced leisure time is going around. I wish Al all the best, and a quick turnaround.

The Hot Rod Clipper has been a fascinating blog, and it was right at the point of "checking the engine numbers" to see if they matched the build sheet. I just gave a shout to find out if the mystery had been solved. It's a real cliffhanger.

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Oh yes, the fabled Chevy piston slap on startup. Almost standard equipment.

You're more than welcome. I like New Castle BTW.

55 Packardguy: Right now might not be the best time to ask Al about progress on his 56. You might have missed it but in another thread Al stated that he is now un-employed.

John F. Shireman

YES!!! It worked. I owe you a cold beer one day!! Thanks!

Quote: That would make sense. I imagine aluminum metallurgy was still considered in it's infancy then and maybe an early version of all aluminum pistons (which still have issues for some today despite all the advances) would have had much bigger issues then.

The only reference I was going by was posted above and speculating as to the reasons.
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Any references that they suffered from piston slip or warpage? I've heard plenty of original, unrebuilt Packard engines from the mid-20s that are silent, and I've seen original OEM pistons removed that looked good enough to use again, and can't recall ever reading about piston problems. There was a service letter about 1934 suggesting that the "T" slot could be installed either way, though earlier recommendation was that it face the camshaft side of the engine.

EDIT - assuming the cite in the Kimes book about reverting to cast iron is in fact correct, I'd guess it was a very temporary measure. Packard's aluminum pistons were of a very sophisticated design, not much different than those used in all the L-8s right thru 1954.

EDIT - the pictures in the 7th series and up service letters show the aluminum 4-ring piston of the controlled expansion autothermic strut design, and states they were used from (at least) the 6th series. Perhaps Packard tried a cast or forged slug design aluminum piston, got poor results, and changed to cast iron while they quickly sourced an improved design?

If they were autothermic back then and still suffered from warpage, piston slap and wear, then if not casting & foundry it would almost have to be a different design or better alloy.

1932 Eight, Super Eight and Twelve pistons were aluminum, cam-ground and controlled expansion autothermic strut design and believe the use of these dates back at least to the 1st Series Eight in 1924, perhaps much earlier.