Rod and main journal bearing clearances are best measured with which tool?

Measuring rod and main journal bearing clearances effectively is crucial for ensuring proper engine performance and longevity. Plastigage is specifically designed for this purpose, as it provides a simple and accurate way to measure clearance.

When used, Plastigage is placed between the bearing and the journal. Once the bearing cap is tightened to the specified torque, the Plastigage is compressed, and its width at the point of compression corresponds directly to the clearance. This is particularly beneficial because it offers a direct visual representation of the clearance, making it easy to interpret the measurements.

Other tools have their own specific applications but may not provide the same level of ease or accuracy for this particular measurement. For example, dial indicators are ideal for measuring movement or displacement but can be cumbersome in confined spaces like engine bearing clearances. Similarly, tram gauges are typically used for aligning surfaces rather than measuring small gaps or clearances. Snap gauges can measure widths but do not clearly indicate clearance in a bearing context, as they require more setup and may not be as straightforward to read.

Thus, Plastigage stands out as the most appropriate tool for measuring rod and main journal bearing clearances due to its accuracy, ease of use, and direct visual results.