Valve: Service and Repair
GRINDING1. Grind the valves at a 45 degree angle.
2. Install the refaced valve in the cylinder head.
3. Measure the valve margin. The specifications for minimum valve margin are as follows:
^ Intake valve margin 0.127 mm (0.005 inch)
^ Exhaust valve margin: 0.762 mm (0.030 inch)
4. If the valves are below this specification, replace the valves.
5. Install the valves in the cylinder head.
a. If you are using refaced valves lap the valves into the seats with a fine grinding compound. The refacing and reseating operations should leave the refinished surfaces smooth and true so that minimal lapping is required. Excessive lapping will groove the valve face and prevent a good seat when hot.
b. If you are using new valves, do not lap the valves under any condition.
6. Re-check the valve stem height. If the height is exceeded, grind the stem to reach specifications.
7. Test the valves for seat concentricity and tight seating using the following procedure:
a. Coat the valve face lightly with blue dye (3)
b. Turn the valve against the seat.
c. If the valve face is concentric with the valve stem, a mark will be made all around the face. If the face is not concentric with the stem, a mark will be made on only one side of the face.
d. Coat the valve seat lightly with blue dye.
e. Rotate the valve against the seat to determine if the valve seat is concentric with the valve guide and if the valve is seating all the way around.
f. Both of these tests are necessary in order to prove that a proper seat is obtained.