i have no ideas left at this point and i cant put a sb together til i figure out what happened here for sure. i am not totally convinced the bearing clearances were the cause. last 2 engines i put together both had .002" on mains and rods and ran 20/50 in both. no failures and had the same pump. last engine went 8yrs street/strip.
If you had the exact same clearances in this motor as the other 2 motors, and they were fine. I would look at what oil mods I did to the oiling system this time. See if you did or didn't do something right. But these guys know way more than I do otherwise.
