Valve Seat: Service and Repair

Valve seats, refacing




Calculating the maximum permissible refacing dimension
- insert valve and hold firmly against valve seat
- measure distance a between end of valve shaft and upper edge of cylinder head
- calculate refacing dimension b (see example) using the measured distance a (above) and:




Minimum dimension
If the measured distance a is smaller than the minimum dimension, the hydraulic valve lifter will not work and the cylinder head must be replaced




Intake valve seat, refacing
a - diameter 39.2 mm (1.543 in.)
b - maximum permissible refacing dimension
c - approximately 2.0 mm (0.079 in.)
Z - cylinder head lower edge
3O° - upper correction angle
45° - valve seat angle




Exhaust valve seat, refacing
a - diameter 32.4 mm (1.276 in.)
b - maximum permissible refacing dimension
c - approximately 2.0 mm (0.079 in.)
Z - cylinder head lower edge
3O° - upper correction angle
45° - valve seat angle

Exhaust valve seat rings are also made with a narrowed diameter. When refacing make sure radius of the narrowed diameter is not damaged.