Main Bearings
- Support crankshaft at both front and rear and ensure that all bearing caps, other than one being checked, are tight. Starting with rear main bearing cap and working forward, remove one cap at a time and check bearing clearances using Plastigage method.
- If clearances are not within specifications, new bearings are available in standard 0.0005", 0.0010" and 0.0015" undersizes. To replace upper main bearing half, insert a flattened cotter pin or roll out pin in oil passage hole in crankshaft and rotate crankshaft in direction opposite to cranking rotation. Place new upper bearing half on crankshaft journal with locating tang in correct position and rotate shaft to turn bearing into place using tool as in removal. Tighten all main bearing cap bolts and rotate crankshaft to ensure there is no excessive drag.
Courtesy of GENERAL MOTORS COMPANY