My '72 SL 6 block has clearly visible letters on the side of each cylinder (A-F). I understand that the letter indicated how much off the cynder bore was on that cylinder and a piston more closely matching the bore was fitted. Can anyone expand on this? SSDan?

bwhitejr

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'72 Duster (Performance 360)
'83 Ramcharger (Performance 318)
'80 TrailDuster (360)
'80 D-150 Truck (See Below)
CompCams 252S, Holley 390cfm, Offy manifold
Ported, Polished and Gasket Matched
P4286813 Springs,0.040 Overbore,
0.090 Shaved Head

Engine component machining and assembly - sub assembly work was happening in many different locations so there were many inspection steps to insure the proper fits.

Basicly, the bored blocks would get measured and the bore size ID letter was marked on the block.
The pistons / con rod assemblies were also measured and sorted into "lettered" bins, based on their sizes.

The engine assembly line worker simply looked at the marking on the block and installed piston assemblies from the matching lettered bin.
"A" pistons go in "A" holes, "Bs" go into "B" holes, etc.
DD