O.S. Engines 37SZ-H - Manual (Page 9)

16
Front view
CORRECT
Side view
Top surfaces are in the same plane.
Re-align the surfaces as necessary
INCORRECT
Top surfaces are not
in the same plane.
Top surfaces are not in
the same plane.
Engine does not rest firmly.
Make sure that only the under-surfaces of the
engine’s mounting lugs are in contact with the
engine mount. Please note that crankcase volume of
the 37SZ-H is a little larger than the 32SX-H’s. If the
crankcase body touches the mount, chamfer the
edges of the mount.
17
CARBURETOR CONTROLS
With a fixed-wing model, power failure is rarely a
serious threat to the safety of the aircraft since it can
usually glide down to a safe landing. In a helicopter,
on the other hand, it is vitally imporant that the engine
keeps running and that there is a quick and reliable
response to the throttle in order to ensure safe ascent
and descent of the model.
The Needle Valve:
When set to produce maximum power at full throttle,
this establishes the basic fuel/air mixture strength.
This is then maintained by the carburetor's
automatic mixture control system to cover the
engine's requirements at reduced throttle settings.
The Mixture Control Valve
For adjusting the mixture strength at part-throttle
and idling speeds, to obtain steady idling and
smooth acceleration to medium speeds. The Mixture
Control Valve has been factory set for the
approximate best result. First, run the engine as
received, and re-adjust the Mixture Control Valve
only when necessary.
Two adjustable controls are provided on this carburetor.
Needle Valve
MIxture Control Valve
REALIGNMENT OF MIXTURE CONTROL VALVE
In the course of making carburetor adjustments, it is
just possible that the Mixture Control Valve may be
inadvertently screwed in or out too far and thereby
moved beyond its effective adjustment range.
Its basic setting can be reestablished as follows :
Mixture Control Valve
Carburetor Body
First rotate the Mixture
Control Valve until its
slotted head is flush with
the carburetor body.
Then screw the valve in
exactly 1 turn. This is the
standard position. 0.5mm