O.S. Engines Sirius7 FR7-420 - Manual (Page 9)

16
GLOWPLUG HEATING
Glowplug battery
The engine uses seven plugs (O.S. Type F).
It is suggested to use a commercially available glowplug
heater intended for multi-cylinder engines. This enables the
glowplug heat to be turned ON and OFF at the transmitter
and also apply heat at idle. A pulse type that heats the
plugs with lower current drain is suggested.
Since the required consumption current is 7 times more
than that for a single cylinder, a 1.2V, 20A capacity battery
is required.
Glowplug leads
Make sure that no part of the wiring touches any part of the
engine, or the wire covering may be melted which causes
short-circuit and fire.
Insert each plug terminal on the plug until you feel two
“clicks”.
Make sure that the plug terminals do not come off before
heating the plugs.
When the plug terminals come off while running or you feel
contact is loose, it is suggested to replace the plug
terminals.
Be sure to install insulating covering (5 O.D., 3 I.D., 12 long
silicone tubing) when replacing the plug terminals.
Receiver
Connect to
each plug
Earth (ground)
lead
On board plug heater
Battery
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If glowplug leads are extended together as a single cable, use
heavier wire, e.g. cross-section area of 2.0mm multi-strand
copper core as supplied for earth lead.
Earth (ground) lead
Fasten to the
motor mount.
FUEL AND LUBRICATION
Fuel
Suitable fuel for this engine is a methanol based fuel
containing 5~8% nitromethane and 8~10% lubricant.
It is suggested to dilute commercially available 15%
nitromethane and 18% lubricant fuel with methanol half-
and-half to make a 7.5% nitromethane and 9% lubricant
fuel.
When you blend a fuel by yourself, use only good quality
methanol, nitromethane and lubricant.
When it is difficult to judge the needle adjustment due to
propeller size and the fuel used, it is suggested to install a
collector ring (optional extra) and apply a muffler
pressurized fuel feed system. Also, installation of the
carburetor insert supplied with the engine (refer to Page 23)
makes it easier to judge the needle adjustment reaction,
while power drops a little.
When a commercially available 15% nitromethane and 18%
lubricant fuel is used, it is suggested to install the carburetor
insert and preferably apply muffler pressurized fuel feed
system.
Note:
Never use a fuel containing more than 15% nitromethane,
or stable performance will not be obtained and the
tendency for rust will be increased.