Bearing Measurment

Measure the bearing clearance to determine the correct replacement bearing insert size. There are two methods to measure bearing clearance. Method A gives more reliable results and is preferred.
^ Method A yields measurement from which the bearing clearance can be computed.
^ Method B yields the bearing clearance directly. Method B does not give any indication of bearing run-out.

Method A

Important: Do not mix inserts of different nominal size in the same bearing bore.




1. Measure the crankshaft bearing journal diameter with a micrometer in several places, 90 degrees apart. Average the measurements.
2. Measure the crankshaft bearing journal taper and runout.
3. Install the crankshaft bearing inserts.

^ Tighten the bearing cap bolts to specification.

4. Measure the connecting rod inside diameter in the same direction as the length of the rod with an inside micrometer.
5. Measure the crankshaft main bearing inside diameter with an inside micrometer. Select a set of bearing inserts that will produce the desired clearance.
6. If the specified clearances cannot be met, the crankshaft journals must be reconditioned and undersized bearing inserts installed.

Method B


Important: Do not mix inserts of different nominal size in the same bearing bore.




1. Clean the used bearing inserts.
2. Install the used bearing inserts.
3. Place a piece of gauging plastic across the entire bearing width.
4. Install the bearing caps.

Notice: In order to prevent the possibility of cylinder block or crankshaft bearing cap damage, the crankshaft bearing caps are tapped into the cylinder block cavity using a brass, lead, or a leather mallet before the attaching bolts are installed. Do not use attaching bolts to pull the crankshaft bearing caps into the seats. Failure to use this process may damage a cylinder block or a bearing cap.

5. Install the bearing cap bolts to specification.

Important: Do not rotate the crankshaft.

6. Remove the bearing cap, leaving the gauging plastic in place. It does not matter whether the gaging plastic adheres to the journal or to the bearing cap.
7. Measure the gauging plastic at the widest point with the scale printed on the gaging plastic package.
8. Remove the gauging plastic.
9. Select a set of bearing inserts that will produce the desired clearance.