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How to Measure Your Connecting Rods
When rebuilding your bottom end, you want to ensure you have the right clearance on your bottom end bearings. Stacy goes over using Plastigauge get a proper measurement.
About the Plastigauge Kit
The Plastigauge kit is an essential tool for the engine builder. Big-end crank journals are measured for wear with this handy kit. Kit includes: two 4″ Plastigauge PL-C sticks, measuring ruler in millimeters & inches, and information guide.
The PL-C kit is capable of measuring wear tolerances of 0.175-0.5mm or 0.007-0.020″. A short piece of the measuring stick is placed on the journal between the fitted rod bearing and journal. When the connecting rod bolts are torqued to specification, the stick is compressed, and once the rod is removed from the crankshaft journal, a measurement is made of the width of the compressed stick.
The Plastigauge is used to confirm previous measurements made with a micrometer in determining wear on the crankshaft big-end journals. The mechanic can make an accurate decision on whether to have the journals machined undersized, if the results of the measurement suggest wear is present.
The connecting rods must be removed, but measurements can be taken with both the existing rod bearings or new replacement bearings fitted, confirming that the journal diameters are within specification for service.
