GMC 4000 Series Service Manual page 380

and tighten cap nut (10) to 50 to 55 foot-pounds with
torque wrench.
3. Set nozzle holder upright in holding fixture
or vise and insert spindle (6) into holder. Place
spring (1) on spindle, then thread spring pressure
adjusting nut (3) into threads in nozzle holder. Place
cap nut gasket (2) over nut (3), then install cap nut
(4) on threads on adjusting nut (3).
4. Check nozzle on test fixture for spray pat­
tern and valve opening pressure, as explained later
under "Setting Injection Nozzle Valve Opening
Pressure." Spray pattern should be equally spaced
cones having no stringy ends or solid stream ers.
Note also if any leaking or dripping is evident after
injection is completed. If valve does not open at
3,000 psi adjust valve spring pressure.
NOTE: There are four holes in valve body (9).
Two point down and two at right angle in order to
give proper spray pattern.
SETTING INJECTION NOZZLE
VALVE OPENING PRESSURE
Using test pump (J-21770) connected as shown
in figure 22, proceed as instructed to set the valve
opening pressure and test for leaks. Key numbers
in text refer to figure 22.
NOZZLE HOLE
CLEANER
LEAK-OFF
H O SE PLUG
G M C S E R V I C E M A N U A L
FUEL INJECTION SYSTEM— TORO-FLOW ENGINE
NO ZZLE HOLE
NOZZLE HOLE BRUSH
Figure 2 3 — Cylinder H e a d N ozzle W ell C le a n in g Equipm ent
W A RN IN G
Fuel spray from injection nozzle in
operation has sufficient power to puncture
the skin. Keep hands away from nozzle tip
when testing. Fuel which enters blood
stream may cause serious infection.
1. With nozzle holder assembly connected to
tester, actuate the test stand handle (10) rapidly
(about 25 strokes per minute) to expel air from
nozzle and holder and to "settle" the spring and
nozzle loading column.
2. Depress operating handle (10) slowly to
raise pressure. Continue to depress handle and note
the gauge pressure at which the nozzle valve opens.
If opening pressure is not 3000 psi, remove the
leak-off tee and loosen cap nut (7) so Allen wrench
(6) can be used to adjust spring pressure.
3. Use Allen wrench (6) as shown in figure 22,
to turn pressure adjusting nut and change spring
pressure. Turning nut clockwise increases p res­
sure. Repeat valve opening pressure test each
tim e adjusting nut is changed until correct opening
pressure is obtained.
NOZZLE HOLE
BRUSH
Sec. 6M
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