O.S. Engines 91SX-H Competition Special - Manual (Page 7)

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Make sure glowplug element
glows bright red inside room
or shadow.
Battery leads
10 Plug wrench
Used for tightening glowplug. The
O.S. long plug wrench is available
as an optional accessory.
7 Fuel pump
For filling the fuel tank one of the
purpose-made manual or electric fuel
pumps may be used to transfer fuel
directly from your fuel container to the
fuel tank.
For tightening
glowplug
Manual
Electric
Fuel pumps
Fuel Can Filter
12V Battery
Starter
8 Fuel container filter
Install a filter on the outlet tube of your
refuelling container to prevent entry of
foreign matter into the fuel tank
9 Silicone tubing
This is required for the connection
between the fuel tank and engine.
Silicone tubing
6 Electric starter and starter
battery
An electric starter is recom-
mended for starting.
5 Hexagon starting shaft
This shaft mounted on an
electric starting motor is driven
into the shaft cup to turn the
engine.
In case of 1.5volt dry cell
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FACTS ABOUT GLOWPLUGS
The role of the glowplug
Glowplug life
Particularly in the case of very high performance
engines, glowplugs must be regarded as expendable
items.
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 compatibility of glowplug and fuel may have
a marked effect on performance and reliability, it may
be worthwhile to choose the R/C type plug found
most suitable after tests. Recommended O.S. plugs
are No.8 and A5. Carefully install plug finger-tight,
before final tightening with the correct size plug
wrench.
Install a plug suitable for the engine.
Use fuel containing a moderate percentage of
nitromethane.
Do not run the engine too lean and do not leave the
battery connected while adjusting the needle.
However, plug life can be extended and engine
performance maintained by careful use, i.e.:
Apart from when actually burned out, a plug may
need to be replaced because it no longer delivers its
best performance, such as when:
When to replace the glowplug
Filament surface has roughened and turned white.
Filament coil has become distorted.
Foreign matter has adhered to filament or plug
body has corroded.
Engine tends to cut out when idling.
Starting qualities deteriorate.