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Valve, grinding
Valves tightening angles:
Inlet: 29.5°
Exhaust: 44.5°
Check valves before grinding. If there is cracking,
damage to the crown or bent valve shafts the valves
must be replaced. Grind the sealing area as little as
possible, although sufficiently that it is cleaned all
round. If the valve crown edge (G) is less than 1.2
mm for the 44/300 series, or 1.7 mm for the 31/32/
41/42/43 series, after grinding the valve must be re-
placed.
Always grind in the mating surface (even on new
valves and seats) with lapping paste and check the
mating surface with marker ink. If the seal is bad
grind the seat, but not the valve, again using the lap-
ping paste and check with marker ink.
Check the distance (A) between the cylinder head
surface and the valve crown according to point 1
under the operation “Valve seat replacement”.
Repair Instructions
Valve seat, grinding
Before grinding the valve guides should be checked
and replaced if the wear parameters are exceeded.
When grinding the valve seat only remove the min-
imum amount necessary to ensure that the valve
seat has the right shape and surface form.
Valve and valve seat
Mill or grind the valve seats. A new seat must be
ground so that the distance between the cylinder
head level and the valve crown surface (A) measured
with a new valve is:
31/32/41/42/43 42A/B* 44/300
Intake 0.05–0.45 mm 0.25–0.65 mm 1.0–1.4 mm
Exhaust 0.05–0.45 mm 0.25–0.65 mm 0.9–1.3 mm
* For the 42A/B that the valve crown is above the cylinder head
surface.
A used seat (within wear parameters) must be ground
so that the distance between the cylinder head level
and the valve crown surface (A) measured with a new
valve is:
31/32/41/42/43 42A/B* 44/300
Intake 0,65 mm 0,05 mm 1,6 mm
Exhaust 0,65 mm 0,05 mm 1,5 mm
* For 42A/B the above applies as a minimum measurement.
In case of a larger distance the seats should be re-
placed.
Check the seat angle with a seat pattern after coating
the mating surface with marker ink.
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