Hi All..I'm in the process of rebuilding my 86 L98 because of a rod knock..after tearing it down I descovered that all but #1 piston had broken skirts !!!..Also the inside of the cylinder walls (4 of Them) had a blk pattern on one side like some took a paint brush and spattered it..I talked to my speed shop guy and he said that the engine might have gotten hot sometime in it's life..but as long as the wall are in spec not to worry..I honed and ridge reamed and they are round and within 002 of each other..and in spec..I don't want to put all this $$ into a block that might fail..although everything seems right ..What do you guys think..Sorry it's so long

Id think if there was some serious heat in there then there may be some blue sort of colouring to it too, but im not sure.

If your in spec and there is no damage then you will be fine. I would stroke it out since your rebuilding anyway

Mag the block and hone it with torque plates. If piston to wall clearance exceeds .0025, a cast piston will be quite noisy.

Rod knock, busted skirts, sounds like serious detonation was going on there! the stock pistons are cheesey hypereutechtics and shatter not melt when extreme detonation is going on. do not ignore spark knock! or someone blasted it with nawzzz? ridge ream? self honed with what? a berry hone? What were the cylinders checked with ?listen to PeteK and while your at it get the reciprocating assembly balanced, chamfer oil holes, and get the block decked (for squish) if needed as well as line honed if mains are off. Aloha