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Well, I can't believe it! Someone found me a set of piston expanders! 320201. I also read my Glenn engine rebuilding manual, and now I understand how knurling, and the piston expanders work. They go in just under the oil ring, to expand the middle part of the piston where the cylinder is more tapered. Knurling works the same way. I have a couple of shops that I can call on Monday to see if they still knurl pistons.

Other than a few more inspections once I find out about the knurling, and some cleaning, I should ready for reassembly. All the parts are shipped!

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Looks like I need some tappet screws too. Otherwise cleaning is going well...

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Factory valves are flat on top so curious about those you showed. Are there any identification numbers on them?

Holy cow! I thought they were stamped "PMC" - they are actually stamped "DMVC". The exhaust are stamped "DMVC EX" and the intakes are stamped "IN 8 DMVC".

No other numbers.

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The one on the left in the foreground appears to
have an "IH" which looks to me like International Harvester.
Of course Ken is correct that is an"N".

Packard Don,
I think the slot is for engaging with a valve lapping tool.

Yes, I know even though I've never had slotted valves. For my Packard flat valves, I use the lapper with the suction cup.

Ken, are there any markings or numbers under the head?

Don, no markings on the underside of any of the valves.

question on 324090 tappet adjusting screws...some are machined concave on top some flush, some raised above head. Comments?

To knurl or not to knurl...

So, I have a set of piston expanders, and they look good. I also found a guy who can knurl the pistons... but ... he doesn't want the block in his shop (because it has a car attached!!! ) and I'm concerned about having him knurl the pistons without the block to compare it to. Thoughts?

I also ordered the piston rings, then noticed in the shop manual where it specifies a different type of piston ring (specifically the top ring) when piston expanders are used. It is an expansion type ring with a groove on the inner diameter of the top of the top ring, to aid in sealing. So, if I can find a set of those rings, I'll probably run the expanders. If I can't, I might risk knurling, knowing some hand work would be required if he takes a piston too far.

Anyone with more experience have any suggestions or good ideas? Not planning on making any decisions until I get back from my valve grinding excursion this weekend.