Mitsubishi S4S Service Manual page 71

(b) Using lapping tool, hold the valve against the
seat and rotate it only a part of a turn, then
raise the valve off the seat, rotating it to a new
position. Then press the valve against the seat
for another part of a turn. Repeat this operation
until the compound wears and loses it cutting
particle.
(c) Wash off the compound with diesel fuel.
(d) Apply the valve face to the engine oil, and
again lap the valve.
(e) Check the valve face for contact.
(9) Measuring valve spring perpendicularity and free
length
Measure the free length and perpendicularity of
each valve spring. If the free length or
perpendicularity exceeds the service limit,
replace the spring.
Unit: mm [in.]
Item
Assembly Service
Standard Limit
Free length 48.85 [1.92] 47.60 [1.87]
Perpendicularity
1.5° or less
-
Set length 43 [1.69] -
Set force
176 to 196 147
N (kgf) [lbf]
(18 to 20) (15)
[40 to 44] [33]
ENGiNE MAiN PARTS
Valve lapping
tooI
Lapping valve in valve set
Perpendicularity
Measuring valve spring perpendicularity and free length
7-9