Service manual

G420F(FE) Service Manual Chapter 3. Engine Mechanical System 69
3. Measure the clearance between the valve stem
and guide and if the measured value exceeds the
limit, replace the valve guide and valve.
Valve stem and guide clearance
Intake 0.02 ~ 0.05mm
Standard
Exhaust 0.035 ~ 0.065mm
Intake 0.1mm
Limit
Exhaust 0.13mm
VALVE SPRING
1. Measure free height of the valve spring and
replace the spring if the measured value exceeds
the limit.
2. Using a square, measure squareness of each
spring and replace it if the measured value is out
of squareness excessively.
Valve spring
Free height 48.86mm
Installed load 18.3kg / 39mm
Compressed load 40.0kg / 30.5mm
Standard
Out-of-squareness 1.5°or less
Free height -1.0mm
Limit
Out-of-squareness 3°
VALVE SEAT CORRECTION
Check the valve seat for overheat and inspect
contact with valve surface. Correct or replace it if
necessary. When correcting, check the valve guide
for wear, if it is worn, replace the guide and correct
the seat ring. Using a grinder or a cutter, correct the
valve seat to make the seat contact width to the
standard. When correcting the exhaust valve seat,
must use the valve seat voce and pilot, after
correcting, must apply a light coat of compound to
the valve and valve seat.