D
Valve seat repair:
A valve seat not producing a uniform contact with its valve or
showing width of seating contact that is out of specified range
must be repaired by regrinding or by cutting and regrinding and
finished by lapping.
1) EXHAUST VALVE SEAT: Use valve seat cutter (1) to make
two cuts as illustrated in figure. Two cutters must be used: the
first for making 15
_
angle, and the second for making 45
_
angle. The second cut must be made to produce desired seat
width.
Seat width for exhaust valve seat:
1.65 – 2.05 mm (0.0650 – 0.0807 in.)
2) INTAKE VALVE SEAT: Cutting sequence is the same as for
exhaust valve seats (1).
Seat width for intake valve seat:
1.80 – 2.20 mm (0.0709 – 0.0866 in.)
3) VALVE LAPPING: Lap valve on seat in two steps, first with
coarse size lapping compound applied to face and the se-
cond with fine-size compound, each time using valve lapper
according to usual lapping method.
Cylinder Head
D
Remove all carbon from combustion chambers.
NOTE:
Do not use any sharp-edged tool to scrape off carbon. Be
careful not to scuff or nick metal surfaces when decarbon-
ing. The same applies to valves and valve seats, too.
D
Check cylinder head for cracks in intake and exhaust ports, com-
bustion chambers, and head surface.
6A1-36
ENGINE MECHANICAL (F8D ENGINE)
