1942 - 1947 Chevrolet Shop Manual



	7-17

	Replacement 1. Assemble a rubber cushion and steel retainer on the cylinder mounting stud; insert the stud through the hole in the bracket and install a steel retainer, rubber cushion, flat washer, and castle nut on the mounting stud in the order named. Tighten the nut just enough to permit inserting the cotter pin and no more. It is essential that flexibility be maintained at this point. 2. Connect the valve link and piston rod yoke according to instructions given under the heading "Reactionary Levers." 3. Install the vacuum and air hoses and tighten the hose clamps. Lubrication When it becomes necessary to lubricate the vacuum cylinder it must be removed because of its mounting angle. With the cylinder set up on its mounting end, pull the valve link forward to open the vacuum port on the forward side of the piston, and, while holding the link, introduce 1/2 ounce of shock insulating fluid into the cylinder through the vacuum inlet stack. Allow sufficient time for the fluid to flow down into the cylinder. Push the valve rod all the way into the piston rod, and introduce 1/2ounce of shock insulating fluid through the vacuum inlet stack. Again allow sufficient time for the fluid to flow down into the cylinder. Move the piston rod in and out of the cylinder several times, at the same time turning the cylinder to spread the fluid over the cylinder walls and piston leather. Then reassemble the cylinder to its bracket, and connect the piston rod yoke and valve link to the reactionary lever system. Washing To wash the cylinder internally without disassembling, follow the instructions under "Lubrication" with the following exceptions: Two ounces of shock insulating fluid should be injected into the cylinder through the vacuum inlet stack. After the piston rod has been moved back and forth several times, hold the piston in the down position and move the valve to allow the fluid to drain out through the valve ports. Repeat the process, after which the fluid remaining in the cylinder after draining should be of sufficient quantity and cleanliness to lubricate the cylinder. AIR CLEANER Every 10,000 miles the air cleaner should be removed and cleaned as follows: Disconnect the air hose from the vacuum cylinder. Remove the	two bolts which attach the air cleaner to the frame side rail. Wash it in clean gasoline or cleaning solvent. Allow the gasoline to drain off and dip it in engine oil. Allow the excess oil to drain off and reinstall the air cleaner to the frame side rail, making sure the soft rubber gasket is in place. VACUUM CYLINDER VALVE ADJUSTMENT Should it become necessary to adjust the valve in the vacuum cylinder the procedure outlined below must be followed very closely: 1. Slip the forward end of the rubber boot off the rear end of the reactionary lever metal boot. 2. Remove the two screws which fasten the two halves of the metal boot together, and remove the outer half, exposing the reactionary levers. 3. Remove the piston rod yoke clevis pin. Push the piston rod into the cylinder far enough to disconnect the yoke and valve from the reactionary levers. Install the special adjusting bushing J1452-5, and replace the clevis pin. 4. With the engine running, to provide vacuum, move the valve link away from the cylinder until all clearance between the special adjusting bushing and the valve link is toward the front of the car as shown at "A¹' in Fig. 30.

		Fig. 30—Valve Links Away From the Cylinder In this position the piston rod should move slowly outward. Now move the valve link toward the cylinder until all clearance between the adjusting bushing and the valve link is toward the rear of the car as shown at "B" in Fig. 31. In this position the piston rod should move slowly inward. Should the piston move outward but will not move inward, the valve link is adjusted too far towards the cylinder on the valve rod. To correct this condition, remove the clevis pin and unscrew the valve link on the valve rod 1/2 turn at a time until proper valve action is obtained. On the other hand, if the piston