O.S. Engines 108FSR - Manual (Page 12)

Be sure to use a pressurized fuel system by
connecting the muffler pressure nipple to the vent-
pipe of the fuel tank.
FUEL TANK LOCATION
•
Attention to tank height
Fuel level
10mm
For installation in the model a 500cc tank is
Suggested. These will allow 10-12 minute flights.
Locate the fuel tank so that the top of the tank is 5-
10mm (1/4-3/8") above the level of the needle-valve.
The role of the glowplug
With a glowplug engine, ignition is initiated by the
application of a 1.5-volt power source. When the battery
is disconnected, the heat retained within the combustion
chamber remains sufficient to keep the plug filament
glowing, thereby continuing to keep the engine running.
Ignition timing is 'automatic' : under reduced load,
allowing higher rpm, the plug becomes hotter and,
appropriately, fires the fuel/air charge earlier;
conversely, at reduced rpm, the plug become cooler and
ignition is retarded.
Since the glowplug and fuel combination used may
have a marked effect on performance and reliability, it
would be worthwhile to experiment with different plug
types.
Recommended O.S. plug is No8.
Carefully install plug finger-tight, before final tighten-
ing with the correct size plug wrench.
GLOWPLUG
11