I assume (yep, I know what that makes you and me) that Jon's "30 over" is intended to mean "undersize" on the bearings. If the bearing and the shaft is matched up properly, the actual undersize is irrelevant. I like to shoot for a .0015" oil clearance. Stovebolt main bearings were available in sizes as small as .050" undersize, and I've seen 40 under rod bearings at times. It's far more important to make sure the hole the bearing fits is round, and the proper diameter. I recondition every used rod I put into an engine, down to the minimum factory specification. Ditto for main bearing bores whenever possible. Finding a machinist willing to line bore a stovebolt block with four different main bearing diameters is about as likely as finding a chicken with lips, which is why I bought my own portable line bore machine. I've also got a Sunnen connecting rod hone. The Rube Goldberg stroker engines I'm building will have a connecting rod journal almost 1/4" smaller than the original stovebolt rod bearing, yet those Nissan bearings are used on 800+ HP turbocharged engines.
Jerry
