The "Chilton" shop manuals go a bit further in explaining some of the problems with converting from babbit rod bearings to inserts.
Chilton manuals covering 1940 thru 1955 state the importance of checking crankshaft/rod journals for out-of-round on the full pressure conversion...too much causes excess oil to over-splash into cylinder walls... Versus...too tight a fit and no splash to lube the cylinder walls, pistons, pins, rings. Crankshaft main bearing out-of-round NOT to exceed .003. Connecting rod within .002 Sometimes Chilton says regrind crankshaft when ANY journal exceeds .0015 in. "Use a pair of micrometers and mike the journals in at least 4 places and average the reading."
Chilton manuals also say that " fit the rod bearing & adjust BEFORE new rings are installed". Adjust ALL 6 rod bearing clearances THEN remove the pistons and install rings. The "why" is because "new rings are so tight that it is very difficult to turn the crankshaft...and thus difficult to adjust rod bearing clearance due to "ring-drag".
Hope this helps... Its old time stuff from an old book...
{Source; Your Complete Handbook On How To Fix Chevrolets, a Chilton Book 1955}
[ 01-03-2002: Message edited by: lil' johnny ]
