Jeep UNIVERSAL CJ-2A - Low-Speed Circuit

'Jeep' UNIVERSAL and 'Jeep' DISPATCHER
F
Specified clearances:
CJ-3B, CJ-5, CJ-6 ........... %" [7,93 mm.]
DJ-3A ...................... %'2" [7,14 mm.]
This clearance, shown as A in Fig. 123, can be
measured by a gauge.
Use these Carter Gauges:
CJ-3B, C]-5, C]-6 .. .............. T109-107
DJ-3A ........................... T109-126
F-17. Low-Speed Circuit
Fuel for idle and early part-throttle operation is
metered through the low-speed circuit. The low-
speed circuit is illustrated in Fig. 124. Liquid fuel
enters the idle well through the metering rod jet.
-Low-speed jet measures the amount of fuel for
FIG. 124-LOW-SPEED CIRCUIT
1-Body Flange
2-Idle Adjustment Screw Port
3-Idle Port
4-Idle Well
S-Low Speed Jet
6- Idle Air Bleed
7-Air By-pass
8-Economizer
9-Metering Rod Jet
10-Idle Adjustment Screw
idle and early part-throttle operation. Air-by-pass,
economizer, and idle air bleed are carefully cali-
brated orifices which serve to break up the liquid
fuel and mix it with air as it moves through the
passage to the idle port and idle ad.iustment screw
port.
F-18. Idle Adjustment
Turn screw, Fig. 124, % to 1% turns for normal
opening on the CJ-3B, CJ-5, CJ-6. Turn screw 1
to 272 turns for normal opening on the DJ-3A
carburetor. For richer mixture, turn this screw
out; for leaner mixture, turn this screw in. Do not
idle the engine below 600 rpm. By-pass, economizer,
idle
port, idle adjustment screw port, and bore of
throttle body flange must be clean and free from
carhop.. Obstructions at any of these points will
cause poor low-speed performance. A worn or
damaged idle adjustment screw or low-speed jet
should be replaced.
FIG. 125--HIGH-SPEED CIRCUIT
1-Nozzle
2-Metering Rod
3-Pump Lifter Link
4-Metering Rod Arm Assembly
5-Diaphragm Shaft
6-Upper Pump Spring
7-Pump Diaphragm Spring
8-Diaphragm Assembly
9-Chamber
10-Metering Rod Jet
11-Carburetor Casting
12-Carburetor Bore
F-19. High-Speed Circuit
Fuel for part-throttle and full-throttle opera-
tion is supplied through the high-speed circuit
shown in Fig. 125. A metering rod and metering
rod jet control the amount of fuel admitted
through the nozzle for high-speed operation.
The lower end of the metering rod is calibrated in
size to accurately meter the fuel required. As the
rod is automatically raised and lowered in the jet,
the opening in the jet is varied in size to supply
fuel proportionate to the requirements through the
higher speed and power range. The metering rod
is both mechanically and vacuum controlled and is
attached to the metering rod arm assembly.
During part-throttle operation, vacuum in chamber
pulls diaphragm down, holding metering arm
assembly against pump lifter link.
Moven;tent of the metering rod is controlled by the
pump lifter link which is attached to the carburetor
throttle shaft. At all times vacuum in the chamber
is strong enough to overcome the tension of pump
diaphragm spring. Upper pump spring serves as
a bumper upon deceleration and as a delayed
action spring upon acceleration. Under any operat-
ing conditio~, when the pump diaphragm spring
overcomes vacuum in the chamber, the metering
rod will move toward the wide throttle (power)
position.
Note: Nozzle is pressed in and should not be
~removed.
F -20. Metering Rod 4\djustment
Check metering rod adjustment each time the
carburetor is reassembled. Before adjustment is
made, be sure that the flat of metering rod arm
is parallel to the flat of pump lifter link as shown
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