LA 360 - 0.030" Undersize Main Bearing Clearance Questions

junkyardhero said

dan, you did know that cars rolled off the assembly line with factory produced engines that were 10 on the crank, or 20 over on the cylinder, right? you think there wasn't ones rolling out that weren't 20 or 30?

yes, before the advent of cheap and/or available stroker kits cutting the journals for chevy rods was a common practice, as was offset grinding mains for more stroke. and that's offset grinding cast cranks.

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I'm not saying that cars didn't roll off the assembly line bored 0.020", and I'm sure that you have done more engines than I have but one thing that's for sure is that all of the engines that I have worked on all where a standard bore and I know this because of two reasons, first my dad always miked the bores and there was never any markings on the pistons. The only one that I was ever told that was bored by the factory was when GM supposedly bored the 396 to a 402. We used well known machine shops for all of the machine work that we needed done, now this was back in the mid '70's through the early '80's and none of them even turned a crankshaft 0.020" that I know of, at least they never did on any crankshafts that they did for us. Boring blocks 0.060" over, I have direct personal experience with that and it wasn't nothing but a over heating night mare.