O.S. Engines 25LA - Manual (Page 15)

Inatall a plug suitable for the engine.
Use fuel containing a moderate percentage of
nitromethane unless more is essential for racing
events.
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.
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STARTING THE ENGINE
Preparations
1 Installing the glowplug
Install washer on the glowplug
and insert carefully into cylinder-
head, making sure that it is not
crossthreaded before tightening
firmly.
Glow plug
Washer 2 Installing the propeller
First, install the propeller on the engine by tightening
the prop nut or spinner-nut lightly, and make sure of
the position where compression is felt, turning the
propeller counter-clockwise slowly. Then tighten
firmly as explained below.
Glowplug life
Particularly in the case of very high performance
engines, glowplugs must be regarded as expendable
For accurately centering the
starter's rubber drive insert,
install an O.S. solid alloy
spinner-nut to the engine.
(Available as an optional extra
part).
Alternatively, a spinner
assembly, enclosing the
propeller boss, may be
used, but make sure
that it isof sturdy
construction and that the spinner shell does not
loosen when the starter is used.
Wrench
14