Block stampings under oil pan gasket area

[Bill B.]

I was going thru my pictures taken several years ago of my rebuild and was reminded that I could not figure out the meaning or origin of the alpha-numeric stampings on the bottom of my engine block in the attached pictures are about. I'm not the orig owner of my 1970 small block, but I suspect the engine was not rebuilt before I acquired it back in 1977, but can not rule out.

Factory markings or from a rebuilder more than 24 yrs ago?

[Owen L.]

Re: Block stampings under oil pan gasket area

I have the same sort of stampings on my '72 block and asked about them in this thread: https://www.forums.ncrs.org/showthread.php?125127-Number-and-letter-stampings-in-the-Mains-area-1972-454-LS-5&highlight=owen+lowe

(My engine had not been rebuilt as it had the factory pistons and bore diameter, stock camshaft, bearings, head gaskets, etc.)

[Duke W.]

Re: Block stampings under oil pan gasket area

Finish machined OE pistons were segregated by size groups, 4, as I recall, in increments of .0005". Finish machined block cylinder bores were accurately measured and the pan rail was stamped for each cylinder's piston size code.l

Cast pistons were fitted to nominal .001" skirt clearance, and forged pistons .0035"

Owen - the OE big block with iron heads had a steel shim gasket. I believe the thickness was 0.28". Can you please measure yours and report?

[Owen L.]

Re: Block stampings under oil pan gasket area

Owen - the OE big block with iron heads had a steel shim gasket. I believe the thickness was 0.28". Can you please measure yours and report?

I'm sorry that I can't assist with this. The gaskets were discarded decades ago when I first disassembled the engine to begin the rebuild that took 30 years to complete!