If an engine is being rebuilt and the crankshaft connecting rod journals are measured at 2.1032-in., what size bearings should be used if the original size was 2.1228-in.?

To determine the appropriate size of bearings to use after measuring the crankshaft connecting rod journals, it is essential to first establish the difference between the original journal size and the measured size. The original connecting rod journal size was 2.1228 inches, while the measured size is 2.1032 inches.

By subtracting the measured size from the original size, the following calculation is performed:

2.1228 in. (original size) - 2.1032 in. (measured size) = 0.0196 in.

This means that the journal is effectively smaller by 0.0196 inches. When selecting bearings, it is standard practice to round to the nearest size available for achieving a proper fit. Since the journal is 0.0196 inches smaller than the original, it would round to a 0.020-inch undersize bearing.

Using 0.020-inch undersize bearings will ensure the proper clearance between the crankshaft and bearings, allowing for optimal lubrication and operation. Thus, this choice is correct as it fits standard industry practices in engine rebuilds, ensuring longevity and performance of the engine.