A John Deere Model 3010 Engine, a 4-cyl, three-main-bearing, four-stroke Otto-cycle in-line engine, was used in tests measuring crankshaft strains and the deviation of flywheel motion from plane rotation about the axial centerline of the main bearing bores. The crankshaft was run with a 50 lbf and a 127 lbf flywheel at 0.006 in. and 0.008 in. diametral main-bearing clearance over a range of 2000 rpm to 3000 rpm engine speed under no-load conditions.The flywheel exhibited a first-order, forward whirl for all test conditions. Crankshaft stresses were not significantly affected by either the flywheel mass or the main-bearing clearances.