Crankshaft & Main Bearings
- Ensure main bearing caps are numbered for location. Arrow on cap points toward front of engine. Ensure main bearing journals are within specification. See CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS table under ENGINE SPECIFICATIONS.
- Position crankshaft on "V" blocks. Using a dial indicator, check crankshaft runout. If runout is not within specification, replace crankshaft. Install crankshaft in block. Check oil clearance using Plastigage method.
- Check one bearing at a time. If engine is in vehicle, support crankshaft counterweight adjoining bearing being checked. DO NOT position jack under crankshaft pulley. Tighten main bearing cap bolts to specification. See TORQUE SPECIFICATIONS .
- If oil clearance exceeds specification, try using a different combination of main bearings. See SELECTIVE MAIN & ROD BEARINGS table. Use only bearing combinations listed in table.
- If oil clearance cannot be adjusted to standard specification with listed bearing combinations, grind crankshaft and use oversize bearings. Oversize main bearings are available in .010" (.25 mm), .020" (.50 mm) and .030" (.75 mm). Tighten main bearing cap bolts to specification.
SELECTIVE MAIN & ROD BEARINGS
| Amount Of Excess Clearance - In. (mm) |
Use Upper Bearing - In. (mm) |
Use Lower Bearing - In. (mm) |
| 0.0-.0005 (0.0-.013) |
.001 (.025) |
|
| .0005-.0010 (.013-.026) |
.001 (.025) |
.001 (.025) |
| .0010-.0015 (.026-.039) |
.002 (.050) |
.001 (.025) |
| .0015-.0020 (.039-.052) |
.002 (.050) |
.002 (.050) |