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Lapping valves in valve seats
Be sure to lap the valves in the valve seats after the
seats has been replaced.
1. Coat the valve face lightly with a lapping com-
pound.
2.
Lap the valve in the seat using the valve lapper.
Raise the valve off the seat, then rotate the valve
only a partial turn and strike it against the seat.
3. Wash off the compound with diesel fuel.
4. Coat the valve face with engine oil, then lap the
valve again.
5. Check the valve face for contact.
NOTE! Do not permit the compound to come in con-
tact with the valve Stern.
NOTE! Use a compound of 120 to 150 mesh for initial
lapping and a compound finer than 200 mesh for fin-
ish lapping.
NOTE! Mixing the compound with a small amount of
engine oil will facilitate coating.
Valve spring clearance and free length
Measure the free length and clearance of each valve
spring. If the free length or clearance (perpendiculari-
ty) exceeds the service limit, replace the spring.
Free length (A), mm [in.]
Assembly standard ... 73 [2.87]
Service limit .............. 71 [2.80]
Perpendicularity (B), mm [in.]
Service limit .............. 2.2 [0.087] (at end)
Length under test force, mm [in.]
Assembly standard ... 66.0 [2.6]
Test force, N (kgf) [lbf]
Assembly standard ... 289–319 (29.45 to 32.55) [65 to 72]
Group 21 Engine Body
85
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