O.S. Engines 21VZ-M - Manual (Page 10)

18
As the idle mixture control screw is
installed with LOCTITE, it may ini-
tially feel stiff, and it is suggested
to use a littli larger screwdriver. The
screw can be turned only 90 degrees either way. Do not
force to turn further, or it may break or cause trouble.
NOTE 90 degrees 90 degrees
Type 20G Remote-mounting
Needle Valve Assembly
(Optional parts)
It enables the Needle Valve to be installed
separately from the engine in a position where
(especially with a cowled or enclosed engine) it
may be more accessible for adjustment. (See
sketch.) Install as follows:
Remove the needle-valve holder from the
carburetor and fit the plug screw in its place.
Drill a 6mm dia. hole in the required position
on the model and insert the Remote Needle
Valve Assembly. If necessary, install a
suitable mounting plate in the model to
which the Remote Needle Valve Assembly
may be fitted.
You may also use the
Needle Control Lever in
conjunction with the Re-
mote-mounting Needle
Valve Assembly.
Fixing nut Ratchet spring
Needle
Remote needle holder Model or fitting plate
Tube length should be kept as short as
possible.
Remote needle holder
Remote needle nut
Plug screw
Silicone tubing
Needle valve
control lever
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STARTING THE ENGINE & RUNNING-IN ('Breaking-in)
The somewhat violent changes of hull attitude
that occur in running, combined with the fact
that, in boats the fuel tank is often located
some distance from the carburetor, means
that fuel 'head' at the carburettor can vary
and upset running.
Therefore,it is recommended that a muffler
pressurized fuel feed system be used.
PRESSURIZED FUEL SYSTEM
Before starting the engine, always check
the tightness of all the screws and nuts
especially those of joint and movable
parts such as throttle arm. Missing
retightening the loose screws and nuts
often causes the parts breakage that is
capable of harming you.
The following procedure is suitable for these
engines when the fuel containing up to 30%
nitromethane are used.
Fill the tank completely with fuel.
Temporarily remove the glowplug to check
that it glows bright red when energized.
Glow Plug Igniter
Pliers
Element glows when energized.
Replace the plug when the
element does not glow or is
burnt out.
Turn the needle-valve clockwise slowly until
it stops. This is the fully closed position.
Do not force to turn further.