Valve Seats

When resurfacing valve seats on engines with hydraulic cam followers, there is a limit to the amount of material which can be removed. If too much material is removed, the final assembly will leave too little space for the hydraulic cam follower to function correctly. The maximum refacing dimension, the maximum amount of material that can be removed from the valve seat, is calculated from the measurement shown in Fig. 4-27.

Fig. 4-27.

Top view of cylinder head. Dimension a, distance between top of valve stem and upper (gasket) surface of cylinder head, is used to calculate maximum refacing dimensions.

Measure dimension a, and subtract the minimum dimension, as given in Table g. The difference is the maximum amount of material that can be removed from the valve seat.

Table g. Minimum Dimensions for Calculating Valve Seat Refacing Dimensions

Valve seat dimensions are given in the tables that follow. Table i lists dimensions for all gasoline engines, except 16-valve. Table j lists dimensions for 16-valve engines. Table h lists dimensions for diesel and turbo diesel engines.

Table h. Valve seat dimensions (diesel and turbo diesel engines)

Table i. Valve Seat Dimensions (gasoline engines except 16-valve)

Table j. Valve seat dimensions (16-valve engines)