If bearing inserts have been plastigaged, what can be determined?

When bearing inserts are plastigaged, it is a method used to measure the clearance between the bearing and the journal. The plastigage, a small strip of plastic material, is placed between the bearing insert and the journal and then the assembly is compressed. After removing the bearing, the width of the flattened plastigage strip indicates the amount of clearance.

In this case, if the determination is that insert "B" has more clearance, it suggests that the width of the plastigage in that position is greater compared to insert "A." This implies that insert "B" is either less precisely installed, or there is a variation in the dimensions that affects how tightly it fits against the journal. This information is crucial as it helps diagnose potential issues with engine maintenance and can inform decisions on whether to replace or remachine bearings to ensure they are operating within the manufacturer's specified tolerances.

Understanding which insert has more clearance can directly influence the overall performance and longevity of the engine components, making it essential for a mechanic to accurately identify these variations.