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 which is being checked. Tighten main bearing cap bolts to specification. See TORQUE SPECIFICATIONS table.
- 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 standard oil clearance specification cannot be obtained using specified 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
| Excess Clearance In. (mm) |
Use Upper Bearing In. (mm) | Use Lower Bearing In. (mm) | ||
|---|---|---|---|---|
| 0.0-.0005 (0.0-.013) | .001 (.025) | (1) | ||
| .0005-.0010 (.013-.026) | .001 (.025) | .001 (.025) | ||
| .0010-.0015 (.026-.039) | .002 (.050) | .001 (.025) | ||
| .0015-.0020 (.039-.052) | .002 (.050) | .002 (.050) | ||
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