TIlE FUEL SYSTEM
D
Muimum
ad
idliDg
speed adjustments
Before making these adjustments it is imperative
that
the
air
cleaner is correctly serviced
and
fitted,
and
the
engine run until it
has
attained its
nonnal
running
temperature.
Maximllm
speed
(1) Slacken the locknut and unscrew the idling damper,
located
011 the
top
of
the
governor housing, two
complete turns. Tighten the locknut
to
secure the
damper
in
this position. This
will
prevent the idling
damper
interfering with the operation
of
the
metering valve during the setting
of
the maximum
speed.
(2)
Using a tachometer
to
check the engine speed,
adjust
the
maximum speed stop screw
to
give
an
engine maximum light running speed
of
2500
r.p.m.
Fit
the rubber plug, plug retaining plate,
and
set screw (early pumps),
or
locking sleeve (later
pumps),
and
seal
the
screw with wire and lead seal,
using sealing pliers
180
541. Check and adjust the
idling speed.
Idling
speed
(1) With
the
engine stopped, unscrew the idling
damper until it
is
known
to
be
out
of
contact with
the metering valve. Tighten
the
locknut
to
secure
the damper in this position.
(2)
Start
the engine
and
adjust the idling
stop
screw to
give
an
engine idling speed
of
800
rpm.
(3)
Screw in
the
idling damper until the idling speed is
increased slightly, then unscrew the damper one-
third
of
a turn, and tighten the locknut
to
secure it
in position.
(4)
Run
the engine
at
about
2500
r.p.m.
and
release
the throttle
to
test for stalling
and
slow de-
celeration.
(a)
If
the engine stalls, screw in the idling damper
slightly
and
carry
out
a further test.
(b)
If
deceleration
is
slow, the idling damper
should be unscrewed slightly
and
a further
test carried out.
(5) Check the operation
of
the shut-otT control.
NOTE.-After
every adjustment
of
the
idliDg
damper
always ensure
that
the engine is not idling directly on
the
idling damper.
Section D.IS
DFSCRJPTION OF THE FUEL INJECl'ORS
The fuel injectors
are
of
the
Pintaux type, developed for
use with the Ricardo Comet V combustion
chamber
to
assist starting under cold conditions.
The
Pintaus. nozzle
is a pintle-type nozzle having
an
auxiliary
spny
bole
which
directs a spray
of
fuel into
the
hottest zone
of
the
combustion chamber.
The
nozzle consists of two parts, the nozzle valve
and
the nozzle body.
The
nozzle valve takes
the
form
of
a
plunger aceurately lapped
into
the
nozzle body
to
the
closest possible fit, within which
it
will
work freely.
The
inner
end
of
the
valve is reduced in diameter
to
produce a stem
upon
which a valve face is formed, the
stem being
extended
to
form a pin
or
pintle which fits
into a comparatively
la.rpodiameter hole
in
the nozzle
body.
The
auxiliary spray bole is drilled
in
the
nozzle
body
at
an
angle to
the
pintle hole, entering
the
nozzle
seating below the line
of
contact
between
tbe valve and
seat. Fuel
is
fed
to
the
mouth
of
the nozzle through-
vertical drillings
in
the
nozzle body which terminate in
an
annular
gallery
just
above the valve seating.
The
nozzles are beld
in
position
in
the cylinder
.,.
by suitably designed holders, a nozzle
nut
~
the
D.21
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