1942 - 1947 Chevrolet Shop Manual



		6-9 The machining operations are performed on the most up-to-date machines obtainable. The bearing surfaces are ground and polished to a mirror finish, then rolled under heavy pressure to produce a hard, long wearing surface. The crankshaft main bearing journal and connecting rod journal sizes are as follows:—Front, 2.6835"-2.6845"; Front Intermediate, 2.7145"-1.7155"; Rear Intermediate, 2.7455^/'-2.7465"; Rear, 2.7765"-2.7775"; Connecting Rod Journal, 2.311"-2.312". Whenever a crankshaft has been removed from an engine, it is important that these dimensions be checked with a micrometer for out-of-round, taper and undersize. If the journals exceed .001" out-of-round or taper, the crankshaft should be replaced. Slightly undersize journals can be used providing that they are within the above limits for out of round or taper. Any time the crankshaft is removed from the engine it should also be checked for runout. To perform this operation, support the crankshaft at the front and rear main bearing journals in "V" blocks and indicate the runout of both the rear intermediate and front intermediate journals, using a dial indicator. The runout limit of each of these journals is .002". Installing Crankshaft Blow out all cuttings from the bearings. Clean out all oil passages by blowing them out with compressed air. It is good practice to blow out each oil passage separately—this can be done by placing the fingers on the oil hole in three of the bearings while the nozzle of the air gun is placed in the oil inlet of the cylinder block. After blowing out the oil passages of all four bearings, then blow through each of the oil passages from the main bearings to the camshaft bearings. Proper cleaning of all oil passages is very important and must be done thoroughly. Lubricate all four bearings and carefully place the crankshaft in the bearings. Check the end-play by forcing the crankshaft to its extreme rear position. Check at the rear side of the rear intermediate bearing with a feeler gauge, Fig. 15. This clearance should be from .004" to .007". Install the bearing caps with four .002" shims on each side and pull the bolts down snugly. Check to see that the crankshaft rolls freely. Adjusting Main Bearings Starting with the rear bearing, remove shims evenly until there is a slight drag on the crankshaft
	Fig. 13—Rear Main Bearing Oil Seal into the groove. When rolling the seal start at one end and roll it to the center of the groove. Then starting from the other end, again roll toward the center, as shown in Fig. 14.

	Fig. 14—Rolling Rear Bearing Cap Oil Seal into Groove Following the above procedure insures that the seal is firmly pressed into the bottom of the groove. The small portion of the seal which protrudes from the groove at each end after installation should be cut flush with the surface of the bearing cap. To prevent the possibility of pulling the seal out of the groove it is recommended that a round block of wood the same diameter as the crankshaft flange be used to hold the packing firmly in position in the groove while the ends are being cut off. If it should become necessary to replace the upper half of the seal, it will be necessary to remove the engine from the chassis and remove the crankshaft. The procedure for installing the seal in the cylinder block half of the bearing is exactly the same as for installing it in the bearing cap. CRANKSHAFT One of the main reasons for the smooth engine performance of Chevrolet's six-cylinder engine is its rugged crankshaft. It weighs 68 pounds, has heavy counter weights and extra large bearing diameters.