Carburetor Controls; Glowplug - O.S. engine MAX-28XZ Instruction Manual

Carburetor Reducer
Needle Valve
Mixture Control Valve
Thermo Insulator
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
Recommended O.S. plugs are P3 and P4.
Carefully install plug finger-tight, before
final tightening with the correct size plug
wrench.
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.
Four adjustable controls are provided on
this carburetor.
Dust Cover
Throttle Stop
Screw
Ball Link
NOTE: Readjustment may be necessary,
occasionally to allow for changes in fuel
Metering Needle
formula, gear ratio or clutch engagement
point.
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Glowplug life
Particularly in the case of very high performance
engines, glowplugs must be regarded as expendable
items. However, plug life can be extended and engine
after tests.
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:
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CARBURETOR CONTROLS 21J
The Needle-Valve(Adjusted at the factory):
For adjusting the mixture strength when the
throttle is fully open.
The Mixture Control Valve:
For changing the mixture strength at mid
speed and acceleration. (Do not rotate the
screw more chan one turn.)
The Metering Needle:
For adjusting the mixture strength at part-
throttle and idle speed, to obtain steady
idling and smooth acceleration to mid speed.
The Throttle Stop Screw
(Adjusted at the factory):
For setting the minimum idle speed:

GLOWPLUG

Install 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.
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.