1942 - 1947 Chevrolet Shop Manual



	6-18

	The connecting rod and piston should be assembled in the cylinder bore with the piston pin clamp bolt on the camshaft side of the engine. Lubricate either the piston or the cylinder bore and slip the pistons into the bores, using extreme care. Do not force the rings into the bore. Compress the rings with the piston inserter, J-975, and slip the assembly into the bore until the chamfer on the inserter enters the chamfer at the top of the cylinder bore, Fig. 9. With the inserter in this position, the piston rings will readily enter the bore. Lubricate the crankpin and pull the connecting rod down onto it, making sure that the numbered side of the rod is toward the camshaft. Install three .002" shims on each connecting rod bolt and then install the bearing cap with the numbered side toward the camshaft. Install the connecting rod oil dipper with its open side toward the camshaft. Assemble and tighten the nuts. Adjusting Connecting Rod Bearings Remove shims, an equal number from each side of the bearing, until the rod cannot be snapped forward and backward on the crank pin by hand, but can be tapped back and forth with a light blow of an 8 ounce hammer. Then place one .002" shim on one side, being careful to keep the number of shims on each side equal, if possible. When the bearing is properly fitted, it should be possible to snap the rod back and forth on the crank pin with one hand, Fig, 35.	of the crankpin with a feeler gauge. This clearance should not be less than .004" nor more than .011", Fig. 36.

		Fig. 36—Checking Connecting Rod End Clearance Lock the connecting rod bolt nuts by installing new "pal" nuts. The "pal" nuts must be installed with the open side of the nut toward the end of the bolt. Turn the "pal" nut up finger tight and then 1/2 turn more. As a final and last check to be sure that the piston and rod assembly will travel true with the bore, check the clearance between the piston pin end of the connecting rod and the piston pin bosses on the piston with a feeler gauge This should not be less than .025". ENGINE OILING SYSTEM Engine lubrication is supplied by a positive driven gear pump equipped with a spring loaded by-pass valve to control the maximum pressure at high speeds and when the engine oil is heavy and sluggish during cold weather starting. The engine oiling system provides positive pressure lubrication to the main bearings and camshaft bearings. The connecting rod bearings are lubricated at low speeds by means of dippers on the rod bearing caps which dip into oil filled troughs in the oil pan. At high speeds lubrication is amply maintained by oil nozzles. Cylinder walls and pistons are lubricated by the oil spray thrown off by the connecting rods. Lubrication of the valve mechanism is accomplished by oil being pumped to the hollow rocker arm shafts. MAIN AND CAMSHAFT BEARING LUBRICATION The oil flow is from the pan, through the pump screen and oil pump to the block fitting, and then

	Fig. 35—Checking Connecting Rod Bearing Fit If it is not possible to keep the number of shims equal on each side for all bearings, it is preferable to have the greater number of shims on the camshaft side. Check connecting rod end clearance between the upper half of the connecting rod and the side