1942 - 1947 Chevrolet Shop Manual



	*6-4*

	piston pin. The cylinder should be bored to the same diameter as the piston. If a micrometer is not available to measure the piston, the cylinder should be bored .002" less than the oversize piston to be fitted. For example, when fitting a .020" oversize piston, the cylinder should be bored .018" oversize. Cylinder Hone After the cylinder bores have been rebored within .002" of the size desired, they should be finished or polished with a hone, similar to the one shown in Fig. 3.	operation kerosene should be used as a cutting fluid to keep the stones of the hone clean. This same procedure should be followed until the piston being fitted can be pushed through the cylinder on a .002" feeler, using a light pressure, and will lock on a .003" feeler. THE FEELER GAUGE MUST BE PLACED BETWEEN THE PISTON AND CYLINDER WALL ONE-QUARTER OF THE WAY AROUND FROM THE PISTON PIN ENDS, OR AT RIGHT ANGLES TO THE PISTON PIN, Fig. 4. CAUTION—Greater care must be exercised when fitting the slipper skirt pistons because they can be damaged by careless handling. Do not exert heavy pressure on the piston when pushing it into the cylinder bore to check the fit with a feeler gauge. Fitting Piston Pins Chevrolet pistons are sold with the piston pin bushings and piston pins fitted in them. Very seldom will it be found necessary to replace the piston pins due to the bushing becoming excessively worn, but should this operation become necessary, the following procedure should be carefully followed:—

	Fig. 3—Cylinder Hone This is an expanding type hone, with the blades or stones expanding when the nut on the top of the hone is turned. In operation, the hone is placed into the cylinder bore and expanded until it can just be turned by hand. The hone is then operated up and down and rotated clockwise in the bore until it begins to run free. Then the expanding nut, on the top of the hone, is tightened and the hone again operated in the bore until it runs free. During this


		Fig. 5—Reaming Piston Pin Sinkings 1. Place the piston pin bushing reaming fixture in a bench vise. 2. Adjust the expansion reamer for a light cut. 3. Insert the reamer in the piston bushings and start the reamer pilot into the guide in the fixture. 4. Hold the piston in the V-block of the fixture with one hand and turn the reamer handle with the other hand until the reamer has passed through both bushings as shown in Fig. 5.
	Fig. 4— Fitting Pistons