Next we verify that the bearings have correct clearance to the crankshaft. This operation begins by taking measurements around the crankshaft journal. When the crankshaft measurement is set, it is directly transferred to the dial bore gauge. Using this method assures a specific crankshaft to main-bore measurement comparison for correct clearance.
Now, the bearings are set into place and the main cap is torqued down. Jackson noted that the main cap should be seated by tapping it into place with a mallet. Use of a mallet to seat the main cap is important, since seating the cap by torquing the bolts can result in a broken main cap. Once the cap is in place, it is ready to be torqued down.
With the bearings in place and the main cap torqued down, diagonal and vertical measurements are taken in the main bore. For complete accuracy, readings are taken in the vertical location as well as 1-inch diagonally right and left of vertical. This check determines that both the correct bearing clearance and correct bearing eccentricity exists. Jackson noted that if a decreasing number is obtained in the vertical to diagonal measurement, it is an indication of incorrect eccentricity. Should this condition exist, it is imperative to double check the housing bore and the bearings to determine the source of the problem for corrective action. Once the clearance and eccentricity are determined to be correct, this checking process is repeated at each main bore.