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Instructions Valach VM 120 B2-4T
14
Changing the spark plugs
Never tighten the spark plugs on a hot engine! The tension caused by the different
cooling can damage the threat in the cylinder head.
Screw the spark plugs in by hand until the gasket makes contact with the cylinder
head, and tighten them with a wrench a 1/4 turn.
Adjusting the valve gap
On a
cold
engine the valve gap should be 0.1 mm. The adjustments are made with
the supplied feeler gauge, the WS 7 wrench and the WS 2 Hex key.
1. Remove both valve covers.
2. Turn the crankshaft (on the propeller)
until the valves on one cylinder overlap. This
means, that both valves are slightly open, i.e.
one valve begins to open, while the other
starts to close. In this position of the crank-
shaft, you can adjust the valve gap of the
opposite(!)
cylinder.
3. First off all measure the gap with the feeler
gauge (0.1 mm). The gap is OK when the
gauge can easily (without strong resistance)
be pushed through the valve end and the
rocker arm. The gap is to big, if no friction can
be felt. If the gauge sits tight, and can only
be pushed with a lot of resistance, the gap is
too narrow.
4. Loosen the locking nut and place the
feeler gauge between valve end and rocker
arm.
5. Turn the adjusting screw with the Hex key
in small steps, until the gauge can be pushed
with a little resistance though the gap.
6. Tighten the locking nut and check the gap
again with the feeler gauge. It is possible, that
the gap changed after locking the nut.
This photo series shows the adjusting of
the valve gap with the help of the feeler
gauge.
