Valve Face - Inspect; Valve Margin - Inspect; Seat Width - Inspect; Valve Face - Reface - Mitsubishi S12A2 Service Manual

1.5 Valve Face - Inspect

Inspect the valve face after the valve guide is inspected or
replaced.Lap the valve and valve seat whenever valve is
refaced or replaced.

1.5.1 Valve Margin - Inspect

Measure the valve margin.If the value exceeds the limit,
reface or replace the valve with a new one.

1.5.2 Seat Width - Inspect

Apply a thin lead-free coloring paste on the valve face, and
tap the valve face against valve seat with valve lapper to
check the contact condition.If the contact is not even, or any
defects are found, or if the value exceeds the specified limit,
reface or replace the valve or valve seat.
Note: Do not rotate the valve when pressing valve face coat-
ed with lead-free coloring paste against valve seat.
Item
Valve seat angle
Valve Inlet
[0.0780 to 0.0858 in.]
Seat
seat
width
Exhaust
[0.0689 to 0.0768 in.]
Inlet
[0.1063 to 0.1220 in.]
Valve margin
Exhaust
[0.1102 to 0.1260 in.]

1.6 Valve Face - Reface

When the valve is re-used by refacing, use valve refacer.
Note:(a) Grind the valve face with valve refacer adjusted to
the specified angle.
(b) The valve margin is to be within the specified lim-
it.If the dimensions after refacing does not meet the
specified values, replace the valve with a new one.
Chapter 6 INSPECTION AND REPAIR OF BASIC ENGINE
Standard value Limit value
30° -
1.98 to 2.18 mm 2.5 mm
[0.098 in.]
1.75 to 1.95 mm 2.3 mm
[0.09 in.]
2.7 to 3.1 mm
2.0 mm
[0.078 in.]
2.8 to 3.2 mm
Seat width
Valve sinkage
Valve Face - Inspect
Valve lapper
P/N:30091-08800
Seat Width - Inspect
Good
Contact condition between valve seat and valve
Valve refacer
Valve Face - Reface
Valve margin
Lapping
compound
Bad
Grind valve face
at specified angles.
6-5