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Fue/ lnjection System-continued
Page 512
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the atomiser nozzle should he cLean and bnght,
free from damage, likewise the under-surface .. C ,.
of the flan ge, the face of the atomiser body" D ..
4nd the interior retaining shoulder of the nozzle
holder cap nut. All of these must register together
absolutely cLeanly and squarely to fonn the high
pressure joint between the atomiser body and
nozzle.
The atomiser body should now he removed
from the plate, and together with the cap nut
immersed in clean paraffin and left to soak in a
suitable container. The nozzle valve should be
grasped by the stalk between finger and thumb
and withdrawn, carefully, for examination. The
stem of the nozzle valve should be clean and
bright, and free from high spots, bad scratches
or dull patches, and the grooves free from dirt.
meta! particles or other foreign matter.
The stem and the valve scat of the nozzl~
valve should now be examined, and if dirty, or
.. coked" cleaned until bright metal is shown.
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upon to walk in the engine more slowly than 250
injections per minute. Thus by taking the atomiser
spray at 20 strokes per minute, ample margin is
allowed.
When removing an atomiser from the testing
pump close valve by rotating !he hand-wheel and
screw olf the union nut a little at a time so that
the pressure raIls gradually.
Atomisers are set to operate at th~ pressures
described previously before leaving the works. If a
ncw atomiser nozzle is fitted to an atomiser body
it is necessary to reset the pressure. After the
atomiser bas been in service fOT same time, the
opening pressure tends to raIl, but provided that
the atomiser nozzle holes do not choke up, there
is no need to adjust the pressure.
NO ATTEMPT SHOULD BE MADE TO
ADJUST
THE
INJECTION
PRESSURE
WITHOUT
A
PROPER TESTING
PUMP
AND PRESSURE GAUGE AS DESCRIBED
AND
ILLUSTRATED.
IT
IS
QUITE
IMPOSSIBLE TO ADJUST THE SETTING
OF ATOMISERS WITH ANY DEGREE OF
ACCURACY
WITHOUT
PROPER EQUIP-
MENT.
If the atomisers are interfered with, on the
assumption that so maar turns of the adjusting
screw represents so maar pounds, they may vary
as much as 200 pounds as between oae and another.
With such differences between atomisers the engine
cannot possibly give of its best.
If the spray is still unsatisfactory, even af ter
brushing the carbon away. from around the
atomiser nozzle. with the fine wire brush specially
designed for the purpose and illustrated in Fig. S.9,
the atomiser should be placed on the atomiser
holding plate already described, see Fig. S.6.
Before attempting to dismantle the atomiser,
the tension on the spring should be released by
unscrewing the compression screw 38. The nozzle
holder cap nut, 43, Fig. S.ll, should be slackened
with the special ring spanner provided, ETll6
(see Fig. S.IO). To hold the nozzle holder cap nut
in the vice or to use ill-fitting
,.
packed .. or adjus-
table spanners or wrenches is to invite disaster.
Examine the pressure face of the nozzle holder
cap nut to see it is not damaged so as to have
c. nipped" the atomiser nozzle in any way.
The nozzle holder cap nut should aow be
removed and the atomiser nozzle completely lifted
from the atomiser body fOT examination. The
surf aces
cc A" and .. B .. in Fig. S8, on the top of
Cleaning.
Assuming that the nozzle valve bas been soaking
and the two surfaces .. A" and .. B" on the top
of the atomiser nozzle flange already mentioned,
are clean and free from damage, the inside of the
atomiser nozzle should he examined. The kit of
tools shown in Figs. S9 and SlO, are recomrnended.
The three small drilled passages .. G" (Fig. S8),
should be explored to see that they are clear and
clean, followed by an examination of the valve
stem bore in which the nozzle valve slides. This
surf ace should be clean and bright and free from
high spots or scratches or dull patches. The
valve seating .. 1" (Fig. S8) should now come
under observation under a strong light to ascer-
tain whether or not it is free from dirt or carbon.
If this is not so, and indeed, in any case, it is
advisablc to usc tbc soft brass scat scraper No.
ETO70 (scc Fig. S9) to remove any carbon or
particles that may he imprisoned on the scat.
The gallery .. H" (Fig. S8) should ncw be cleancd
with tbc ajd of the special soft brass scraper No.
ETO71 (sec Fig. S9) to ensure that it is also clean
and frec from dirt or carbon.
The spray holes in tbc atomiser nozzle end
should he pro bed with thc special tooi ET120 (see
Fig. S9).
In cases where the holes cannot be cleaned by
this process, the complete atomiscr should be
rctumed securcly wrapped and packed as described
..
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