Regal V6-191 3.1L VIN M SFI (1995)
Crankshaft Main Bearing: Service and Repair
Fig. 10 Main Bearing Insert Markings
Engine bearings are of the precision insert type. They are available for service use in standard and various undersizes, Fig.10.
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 runout, which should be 0.0002 inch (maximum).
3. Install bearing inserts and tighten rod and main bearing cap bolts to specifications, 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.