Connecting Rod Bearing: Service and Repair

Fig. 21 Main Bearing Insert Markings:

Engine bearings are of the precision insert type. They are available for service use in standard and various undersizes, Fig. 21.
To determine correct replacement insert size, bearing clearance must be measured as follows:
1. Measure crankshaft journal diameter in several places, approximately 90° apart and average the measurements.
2. Measure taper and run-out, which should be .0002 inch (maximum).
3. Install bearing inserts and torque rod and main bearing cap bolts to specification, then measure I.D. with an inside micrometer. Measure connecting rod I.D. in same direction as length of rod.
4. Select a suitable set of inserts to provide specified clearance limits. Do not mix inserts of different nominal size in same bearing bore. If clearance limits cannot be met, crankshaft journal must be reconditioned and undersized bearing inserts installed.