Mitsubishi 4G1 Service Manual page 379

Installation
Removal
(4) Check the valve seat sinkage.
height
I
VALVE SEAT REPLACEMENT PROCEDURE
1 EN0274
(2) Rebore the valve seat hole in the cylinder head to a selected
oversize valve seat diameter.
Intake valve seat hole diameter
0.30 O.S.: 44.30 - 44.33 mm (1.7441 - 1.7453 in.)
0.60 O.S.: 44.66 - 44.63 mm (1.7559 - 1.7571 in.)
Exhaust valve seat hole diameter
0.30 O.S.: 38.30 - 38.33 mm (1.5079 - 1.5091 in.)
0.60 O.S.: 38.60 - 38.63 mm (1.5197 - 1.5209 in.)
(3) Before fitting the valve seat, either heat the cylinder head
up to approximately 250°C (482°F) or cool the valve seat in
1 EN027E
liquid nitrogen, to prevent the cylinder head bore from
galling.
specified width and angle.
See "VALVE SEAT RECONDITIONING PROCEDU'RE".
VALVE GUIDE REPLACEMENT PROCEDURE
(2) Using the push rod and a press, remove the valve guide
toward the cylinder head gasket surface.
(3) Rebore the valve guide hole to the new oversize valve guide
outside diameter.
Valve guide hole diameter
Valve
guide
TSB Revision
The valve seat sinkage can be determined by measuring the
valve spring's installed height. (If the valve seat sinkage is
great, the valve seat's installed height also is great.)
If the valve spring's installed height exceeds the service
limit, replace the insert with an oversize part as described
below.
Installed height of spring (both intake and exhaust)
Standard value: 40.4 mm (1.591 in.)
Limit: 41.4 mm (1.630 in.)
wall thickness. Then, remove the valve seat.
0.05 O.S.: 13.05 - 13.07 mm (.5138 - .5'1;45 in.)
0.25 OS.: 13.25 - 13.27 mm (.5217 - .5224 in.)
0.50 O.S.: 13.50 - 13.52 mm (.5315 - .5322 in.)