Measuring Perpendicularity And Free Length Of Valve Spring; Lapping Valve And Valve Seat - Mitsubishi L Series Service Manual

1.6 Measuring perpendicularity and free length
of valve spring
Measure the perpendicularity and free length of the valve
spring. If the limit is exceeded, replace the valve spring with
a new one.
Item
Free length
Perpendicularity
Lf
35.5 [1.3976] / 55.3 to 61.2 N
{5.64 to 6.24 kgf}
[12.4 to 13.8 lbf]
Set length/set
force
28.0 [1.1024] / 138.2 to 152.9 N
{14.09 to 15.59 kgf}
[31.1 to 34.4 lbf]

1.7 Lapping valve and valve seat

Always lap the valve against the valve seat after refacing the
valve seat or after replacing the valve.
(1) Apply a thin coat of lapping compound evenly to the
valve face.
Note: (a) Do not allow the compound to adhere on the
valve stem.
(b) Compound spreads more evenly if it is mixed
with a small amount of engine oil.
(c) Use medium-grain compound (120 to 150 mesh)
for initial lapping, then use fine-grain compound
(200 mesh or finer) for finishing.
(2) Use a valve lapper for lapping. Strike the valve against
the valve seat while rotating the valve little by little.
(3) Wash off the compound using diesel fuel.
(4) Coat the contact surface of the valve with engine oil,
then lap the valve again.
(5) Check valve-to-seat contact.
Standard Limit
40 mm 38.5 mm
[1.57 in.] [1.516 in.]
△ = 2.0
θ = 2.0 °or less
mm
Δ (gap) = 1.4 mm
[0.079 in.]
[0.055 in.] or less
over entire
Lf = 40 mm [1.57 in.]
length
-15 %
INSPECTION AND REPAIR OF BASIC ENGINE
Spring perpendicularity (gap)
Free length
Squareness and free length of spring
Valve lapper
Lapping valve and valve seat
Compound
6-5