1942 - 1947 Chevrolet Shop Manual



	6-8

	12th—Mount the feed screw support bracket "G" on the front boring bar support. Mount the feed screw "I" in its U-shaped yoke and install the screw in the end of the boring bar. Adjust the bar so that the cutters are just about to enter the bearings; then tighten the two feed screw support thumb screws. 13th—Install the turning handle on the end of the boring bar and proceed with the boring operation. During this operation, use a liberal supply of kerosene to keep the cuttings washed out of the bearings. 14th—After the cutters have passed through the bearings, remove turning handle and feed screw. Blow all cuttings out of the bearings with compressed air, being careful not to blow the cuttings into the boring bar support bearings. 15th—Slide the boring bar back until the cutters have passed through the bearings: then again install the feed screw and bore through the bearing a second time. This is very important in order to obtain a perfectly smooth true bearing. 16th— Remove turning handle, feed screw, cutters and boring bar. Do not disturb the boring bar supports because they will be used when facing rear-intermediate bearing for crankshaft end thrust clearance. Rear Intermediate Bearing The rear intermediate main bearing takes the crankshaft end thrust. Therefore it becomes absolutely necessary when replacing main bearings to use an accurate tool to face the flanges of this bearing to the correct width so that the crankshaft will have the proper end thrust clearance. Facing the Rear Intermediate Bearing 1. Install the boring bar through the centering bushing and the rear bearing support. Slip the facing cutters on the boring bar, one on each side of the rear intermediate bearing. 2. Place the feed screw sleeve in the front intermediate bearing and push the boring bar through the sleeve. Install the feed screw drive key through the hole in the sleeve and into No. 2 cutter hole in the boring bar, locking the key in place with its screw. 3. Adjust the feed screws for equal feed range on each side of the front intermediate bearing. Adjust the facing cutters to provide about .015" clearance between the cutter face and the flange of the bearing. Lock the cutters to the boring bar with the clamp screws.	4. Caliper the width of the rear intermediate bearing journal on the crankshaft with the special inside and outside calipers, KMO-964. 5. Install the turning handle on the end of the boring bar. Back off the front feed screw collar several turns and tighten the rear feed screw collar until the front facing cutter contacts the bearing flange. Then proceed with the facing operation, tightening the feed screw as necessary to keep the cutter in contact with the bearing flange. The front flange of the bearing should be machined just enough to thoroughly clean up the face. The proper installation of this tool is shown in Fig. 12.

		Fig. 12—Facing Rear Intermediate Main Bearing 6. Back off the rear feed screw collar and tighten the front collar until the rear cutter engages the bearing rear flange. Then continue with the facing operation, checking the progress of the job every few turns with the special caliper that was set for the width of the crankshaft journal. Continue facing the bearing until the special caliper will pass over the bearing and a .004" feeler laid alongside the bearing flange. Remove the bearing cap and place it on the rear intermediate journal of the crankshaft. Check the end clearance with a feeler gauge; the correct clearance is .004" to .007". 7. Disassemble the facing cutters and boring bar from the cylinder block. All parts of this tool should be thoroughly cleaned and oiled to prevent rusting, and put away in the special boxes provided for this purpose. Crankshaft Rear Bearing Oil Seal Sealing at the crankshaft rear bearing is made very effective due to machining the rear bearing cap and Crankcase to receive a wick-type seal. Fig. 13. To install a new wick seal in the rear main bearing cap, insert the seal in the groove with the fingers. Then using a rounded tool, roll the seal