On further observation of the discoloration of the crankshaft and the bearing shells, I tend to agree that the crank is close to junk condition. It takes a pretty long time of running in a knocking condition and little to no lubrication to cause that much heat damage. I suspect that the oil passage that lubricates those bearings is probably clogged, starving those two rods for oil. I saw a racing engine ruined in the first 5 minutes of operation after a quick assembly job because one of the crankshaft oil galleries had a mud dauber nest blocking it. The engine parts had been stored in a corner of my friend's shop waiting for assembly, and the mud wasps got to the crankshaft passage. The car owner scattered his engine, and quickly assembled the backup without doing a thorough inspection.
Jerry
