I don't know if the guy has the part number mixed up but the part number is speed pro L2348 f. He says they are for a cleve. but i can't find any matching numbers. Thanks for the help.

That is what I have for a part number but mine are TRW. I bought them way back in 1974.Here is a link for them.
http://www.flatlanderracing.com/trwfordsb.html

L2348F is the forged 351C piston with a 12cc pop-up dome originally manufactured by TRW. I don't know if TRW exists any longer as a business in any capacity, but they haven't manufactured automotive pistons in a long time. Federal Mogul evidently purchased the rights to manufacture the old TRW line of pistons. Federal Mogul is the parent company of Speed Pro, Sealed Power, Fel Pro and several others too. The L2348F pistons are actually sold by Sealed Power now, and you'll usually find them sold as Sealed Power/TRW.

Caution however ... I believe Probe industries also sells a rip-off piston with that part number.

-G
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If you use a 351C 4V powered vehicle for a grocery getter ... the eggs aren't going to make it home!

Probe makes a flat top piston they number with the same # P2379F as sealed Power/TRW, but I didn't see the 2348 pop ups.The owner of Probe left J E pistons to open his own Company. I would use Probe Pistons w/o hesitation.

If you perform a search (not on the google search box on this forum) on this forum for L2348 you will find many threads on this piston. I have a new set in a fresh rebuild in my shop.

John

A local guy has them for sale. I'm just wanting to know what the compression would be with oc heads?

Assuming 4.03 bore, 78cc cumbustion chamber volume for the OC heads, .041 gasket thinkness, 4.10 gasket bore, .020 deck clearance and -12cc pop up volume on the piston I get approximately 10.25:1 compression. 76CC head volume gets you closer to 10.5:1 compression.

Deck clearance on the block has a significant effect on compression, for example a zero deck value (instead of .020) in this example would raise the compression to 10.77:1 from 10.25:1 on the 78cc head.