Put the main bearings into the right places in the block and the corresponding caps, and snug the bolts down without the crankshaft in place. Since each bearing is a different diameter, it's virtually impossible to get them in wrong. Remember to install the doweled bearing shells in the right place- - - -the upper and lower bearing shells are NOT identical. The cap should meet the block with little or no torque applied to the bolts. If there's a noticeable gap between the caps and the block surface that would require a lot of torque to close it up, something's wrong. If necessary, a few thousandths of shim can be added between the cap and the block to adjust the oil clearance, so if the crankshaft gets difficult to turn after it's installed, adjust the clearance one bearing at a time. Do this BEFORE installing the rope oil seal at the rear. I like to see about .002" clearance on the main bearings. The Federal-Mogul bearing specification manual lists main bearing clearance at .0005" to .0031", but .0015"-.002" has been the rule of thumb for most of the engine builders I've known for the past 60-something years.
Jerry
