Question

When measuring main bearing bores, provided the vertical reading is not largest, out-of-round measurements are acceptable if less than:

-0.001 inch
-0.010 inch
-0.005 inch
-0.015 inch

Answer 1

Out-of-round measurements for main bearing bores are acceptable if they are less than 0.001 inch, as this ensures the bore has not worn unevenly beyond an acceptable limit. Measurements like 11.1 in., 11.2 in., and 10.9 in.show extreme wear and would not be acceptable.

Step-by-step explanation:

When measuring the diameter of main bearing bores in an engine, it's important to ensure that the measurements fall within a certain tolerance. Out-of-round measurements occur when there is a discrepancy between the largest and smallest diameter readings of a circular bore. According to general engine machining practices, out-of-round measurements for main bearing bores are typically acceptable if they are less than 0.001 inch. This indicates that the bore has not worn unevenly past a threshold that could affect the performance of the engine.

For example, if you take multiple readings around the bearing bore and obtain measurements such as 11.1 in., 11.2 in., and 10.9 in., the variance here is 0.3 in., which is quite large and indicates an out-of-round condition that is unacceptable. The correct value, 11.0 inches, suggests that more accurate measurements would be much closer together, such as 11.01 in., 11.0 in., and 10.99 in., which would be within the acceptable out-of-round tolerance of less than 0.001 inch.