Mitsubishi Lancer Evolution 7. Manual - part 167
ENGINE OVERHAUL -
Cylinder Head and Valve
11B-45
5. VALVE SEAT
Assemble the valve, and measure the amount that the
valve protrudes from the valve shaft end between the
spring seat surfaces when the valve is pressed against
the valve seat. Replace the valve seat if the protrusion
amount exceeds the limit value.
Standard value:
Intake
49.20 mm
Exhaust
48.40 mm
Limit value:
Intake
49.70 mm
Exhaust
48.90 mm
Valve Seat Correction
1. Before correcting the valve seat, inspect the clearance
between the valve guide and valve, and replace the valve
guide if necessary.
2. Correct so that the seat width and seat angle are at the
specified shape.
3. After correcting, apply wrapping compound, and fit the
valve and valve seat together.
Valve Seat Replacement
1. Grind off the valve seat to be replaced from the inside
to reduce the thickness and then remove the valve seat.
2. Machine the valve seat hole on the cylinder head to match
the diameter of the oversized valve seat into which it
is to be pressed in.
Intake valve seat hole diameter:
0.3 O.S.
35.30 - 35.33 mm
0.6 O.S.
35.60 - 35.63 mm
Exhaust valve seat hole diameter:
0.3 O.S.
33.30 - 33.33 mm
0.6 O.S.
33.60 - 33.63 mm
3. When pressing in the valve seat, cool the valve seat
with liquid nitrogen, and make sure that the inner diameter
of the cylinder head is not galled.
4. Refer to the “Valve Seat Correction” procedures, and
machine the valve seat.
Valve shaft end
Spring seat surface
Valve protrusion
amount
10_
65_
10_
65_
0.9 - 1.3 mm
0.9 - 1.3 mm
43.5_ - 44_
43.5_ - 44_
0.5 - 1.0 mm
0.5 - 1.0 mm
Grind off
Valve
seat
height
Oversized hole diameter