Figure 11C-30. Cleaning Injector Nut
Spray Tip Seat
Body Ring
the stick with polishing compound J
23038 and insert it directly into the cen-
to assure the best performance from the
ter of the spray tip until it bottoms.
injector.
Rotate the stick 6 to 12 times, applying a
light pressure with the thumb and fore-
Injector plungers cannot be reworked to
finger.
change the output. Grinding will de-
stroy the hardened case at the helix and
NOTE
result in chipping and seizure or scoring
of the plunger.
Be sure that no compound is acci-
dentally placed on the lapped sur-
Examine the spray tip seating surface of
faces located higher up in the
the injector nut and spray tip for nicks,
spray tip. The slightest lapping
burrs, erosion or brinelling. Reseat the
action on these surfaces can alter
surface or replace the nut or tip if it is
the near-perfect fit between the
s e v e r e l y damaged.
needle valve and tip.
The injector valve spring plays an impor-
tant part in establishing the valve open-
Before reinstalling used injector parts,
ing pressure of the injector assembly.
lap all of the sealing surfaces indicated
Replace a worn or broken spring.
11C-19. It is also good practice to light-
Inspect the sealing surfaces of the injec-
ly lap the sealing surfaces of new injec-
tor
parts
indicated
by
arrows
in
tor parts which may become burred or
nicked during handling.
the sealing surfaces with a magnifying
NOTE
11C-19 for even the slightest imperfec-
tions will prevent the injector from
The sealing surface of spray tips
operating properly. Check for burrs,
is precision lapped by a new proc-
nicks erosion, cracks, shipping and ex-
e s s which leaves the surface with a
cessive wear. Also check for enlarged
dull satin like finish. It is not re-
orifices in the spray tip. Replace dam-
commended to lap the surface of
aged or excessively worn parts. Check
the new current spray tip.
the minimum thickness of the lapped
parts as noted in the chart.
Examine t h e s e a t i n g a r e a o f t h e n e e d l e
L a p p i n g Injector Parts
valve for wear or damage. Also examine
the needle quill and its contact point
Lap the sealing surfaces indicated in
with the valve spring seat. Replace
Figure 11C-31 on page 11C-19, to the
damaged or excessively worn parts.
dimensions shown in the chart attached
to the figure, as follows:
E x a m i n e the needle valve seat area in the
spray tip for foreign material. The smal-
1. Clean the lapping blocks (J 22090)
lest particle of such material can prevent
with compressed air. Do not use a cloth
the needle valve from seating properly.
or any other material for this purpose.
Polish the seat area with polishing stick
J 22964. Coat only the tapered end of