Seat Replacement

VALVE SEATS
- Examine the valve seat inserts for pitting or excess wear. If renewal is necessary, proceed as follows:
- Remove the inserts by machining, leaving approximately 0.25 mm (0.01 in) of metal which can easily be removed by hand without damaging the cylinder head.
- Measure the diameter of the insert recess in the cylinder head.
- Grind down the outside diameter of the new insert to a dimension 0.08 mm (0.003 in) larger than the insert recess.
- Heat the cylinder head for 30 minutes from cold to a temperature of 150°C (300°F).
- Fit the insert ensuring that it beds evenly in the recess.
- Recut when the cylinder head has cooled.
^ Correct valve seat angles are:

Inlet and Exhaust 44.5 degrees

NOTE: If new valve inserts have been fitted, the clearance between valve stem and cam must be checked; this should be 8.13 mm (0.320 in) plus the valve clearance.

- The dimension must be taken between the valve stem and the back of the cam.
- Should this dimension not be obtained, metal must be ground from the valve seat of the insert.

NOTE: Use only suitable grinding equipment

- Remove only very small amounts of metal from the valve seat at one time before rechecking the clearance.