O.S. Engines 91SX-H Competition Special - Manual (Page 6)

10
INSTALLING THE GLOWPLUG
Install the washer on the
glowplug and screw
carefully into cylinder-
head, making sure that it
is not cross-threaded
before tightening firmly.
Glow plug
Washer
INSTALLATION OF THE ENGINE
The under-surfaces of all O.S. engine beam
mounting lugs are precision machined flat and
exactyly parallel to the engine's horizontal axis. It is
essential that the engine mounts in the model are
also accurately made and aligned. If they are not,
they will cause stress and distortion within the engine
itself, probably resulting in loss of performance and
internal damage.
The recommended screws for securing the engine to
the engine mounts in the model are 4mm or 4-40
steel Allen type. It is also advisable to use lock
washers or LOCTITE to prevent nuts from loosening.
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.
11
BEFORE STARTING
Tools, accessories, etc.
The following items are necessary for operating the
engine.
1 Fuel
Select, by practical tests, the most suitable fuel from
among the best quality fuels available in your country
for helicopter use. For the best throttle response, a
fuel containing 10% to 30% nitromethane is
preferable. Lubricants may be either castor-oil or a
suitable synthetic oil (or . a blend of both) provided
that they are always of top quality. For consistent
performance and long engine life, it is essential to use
fuel containing AT LEAST 18% lubricant by volume.
Some fuels containing coloring additives tend to
deterriorate and may adversely affect running
qualities. If in doubt compare to a fuel known to be
good.
Model engine fuel is poisonous. Do not allow
it to come into contact with the eyes or
mouth. Always store it in a clearly marked
container and out of the reach of children.
Reminder!
4 Glowplug battery
The power source for heating the glowplug may be
either a large heavy-duty 1.5volt dry cell, Ni-cd battery
or battery integrated booster.
1.5 volt dry cell
2 Glowplug
O.S. No.8 glowplug is installed in the engine.
3 Battery leads
These are used to conduct current
from the battery to the glowplug.
Basically, two leads, with clips, are
required, but, for greater conve-
nience, twin leads with special
glowplug connectors, as shown on
the right, are commercially available.
Model engine fuel is also highly flammable.
Keep it away from open flame, excessive
heat, sources of sparks, or anything else
which might ignite it. Do not smoke, or allow
anyone else to smoke, near to it.
Battery Integrated booster
Battery leads