Pic. 2.189. Inlet and outlet valves and valve lifters: 1 - camshaft; 2 - adjusting washer; 3 - valve pusher; 4 - valve; 5 - adjusting washer; 6 - cutout; 7 - valve lifter
Reduced diameter valve stems are used to reduce inlet and outlet flow resistance (see fig. 2.189) and to reduce valve weight. The shim is located directly on the valve lifter. This design allows you to change the shim without removing the camshaft, which improves serviceability when adjusting valve clearance. To improve serviceability when replacing shims, there is a cutout in the valve lifter.
Note for service technicians
There are 17 sizes of shims available, in increments of 0.050 mm, ranging from 2.5 to 3.3 mm.