The Chevrolet 350 V-8 engine uses a crankshaft installed in the bottom of the engine under the pistons to change the up and down motion of the pistons into rotary motion for the transmission. The pistons push on parts of the crankshaft which are off-set from the center line of the shaft. Keeping the crankshaft moving smoothly is the job of the main bearings which circle the crankshaft and lubricate it. The bearings are replaced when they wear out or for an engine upgrade. It's a delicate procedure.
Use the hoist to remove the engine from the vehicle. Put the engine on the engine stand and turn it upside down. Remove the oil pan and the main caps. Carefully lift the crankshaft out of the saddles in the engine block.
Wipe the saddles of the block with a lint-free cloth.
Press the half of the bearing that fits in the saddle into place by hand. Match the small tang on the bearing with the notch on the saddle. Make sure the bearing has been placed over the oil supply hole in the saddle.
Examine the bearings. One of them is the thrust bearing and has flanges which keep the crankshaft from moving laterally. Oil those surfaces and put a coating of assembly lube on both halves of the bearing.
Place the feeler gauge from the bearing kit next to the crank. Bolt the main caps in place, then remove them and examine the gauge. It will measure the distance or clearance between the bearing and the crank.
Put the gauge on the bearing and place the crankshaft into the saddles. Set the other halves of the main bearing in their places.
Oil the threads of the bolts and secure them on on the main bearings. Use the torque setting recommended in the engine manual.
Remove the bolts from the upper part of the main bearings and lift off the upper halves. Retrieve the feeler gauge strip. Consult the instructions from the bearing kit to interpret the information from the strip.
Bolt the main bearing down if the clearance is correct. Use the torque settings recommended for the engine.
