Ford Corsar Repair Manual page 71

CYLINDER HEAD
Recess diameter
SEM795A
Inspection (Cont'd)
VALVE SEATS
Check valve seats for any evidence of pitting at valve contact
surface, and reseat or replace if it has worn out excessively.
Before repairing valve seats, check valve and valve guide
for wear. If they have worn, replace them. Then correct
valve seat.
Cut with both hands to uniform the cutting surface.
REPLACING VALVE SEAT FOR SERVICE PARTS
1. Bore out old seat until it collapses. The machine depth stop
should be set so that boring cannot continue beyond the
bottom face of the seat recess in cylinder head.
2. Ream cylinder head recess.
Reaming bore for service valve seat
Oversize [0.5 mm (0.020 in)]:
Intake
36.500
-
36.516 mm (1.4370
-
1.4376 in)
Exhaust
42.500
-
42.516 mm (1.6732
-
1.6739 in)
Reaming should be done to the concentric circles to valve
guide center so that valve seat will have the correct fit.
3. Heat cylinder head to 150 to 160°C (302 to 320°F)
4. Cut or grind valve seat using suitable tool at the specified
dimensions as shown in S.D.S.
5. After cutting, lap valve seat with abrasive compound.
6. Check valve seating condition.
Seat face angle
" a
":
45 deg.
Contacting width "W"
Intake
1.6
-
1.7 mm (0.063
-
0.067 in)
Exhaust
1.7
-
2.1 mm (0.067
-
0.083 in)