Michigan Mechanic Engine Repair Practice Exam 2026 - Complete Test Preparation

To determine the amount of bore taper in an engine cylinder, you need to measure the diameter of the bore at two different points along its length. Typically, this involves taking one measurement at the top of the bore and another measurement at the bottom.

When you denote these measurements as "C" and "D," you're likely representing the diameter at two specific points—usually the top (C) and the bottom (D) of the bore. To find the bore taper, it's necessary to calculate the difference between these two measurements. By subtracting the measurement at the bottom (D) from the measurement at the top (C), you obtain the taper amount. This tells you how much larger (or smaller) the diameter is at one end compared to the other, indicating if there is an undesired taper present which can affect engine performance and sealing with the piston rings.

Thus, the approach of subtracting the bottom measurement from the top is the correct method for calculating bore taper, as it directly shows the variance in size that constitutes the taper itself.