Which of the following measurements is relevant when assessing bore taper?

When assessing bore taper, the key measurement to focus on is the difference between the maximum and minimum diameters. This measurement provides a clear indication of how much variance there is within the cylinder's bore, which is critical in determining whether the bore has worn unevenly.

Bore taper occurs when the diameter of a cylindrical hole is not uniform along its length, often diminishing from the top towards the bottom. By measuring the maximum diameter and the minimum diameter, the technician can establish the extent of this taper. The greater the difference between these two measurements, the more significant the taper, which can adversely affect engine performance.

While other options may involve measurements related to the bore, they do not directly provide an assessment of taper. For instance, measuring only the diameter at the bottom would not consider any variation that occurs higher up in the bore. Similarly, measuring just the smallest diameter might miss critical information about the taper’s condition. Addition of various measurements doesn't specifically indicate the taper’s extent, as it lacks direct correlation to the taper itself. Therefore, focusing on the difference between maximum and minimum diameters is essential for an accurate assessment of bore taper.