Carburetor, Cleaning, Inspection and Repair

TM 10-3930-630-34

5-7. Carburetor, Cleaning, Inspection and Repair

a. Clean all metal parts of the carburetor in cleaning

solvent (Fed. Spec. P-D-680) and dry parts thoroughly.

b. If float valve is grooved or damaged, replace the

float valve and seat.

c. Check for looseness between throttle shaft and

lever assembly and throttle body. If looseness is noted,

replace the throttle shaft and lever assembly.

d. All packings and gaskets should be replaced at

assembly.

e. Replace the idle adjusting needle if grooved or

damaged.

NOTE

Whenever

the

carburetor

Figure 5-3. Carburetor float setting.

overhauled, it is recommended that

kit parts be installed in place of old

NOTE

parts even if damage is not noted.

Do not bend, twist or apply pressure

to float bodies. The float bodies

5-8. Carburetor, Reassembly and Installation

when viewed from the free end of the

a. Reassembly.

bodies, must be centered and at right

(1) Install new packing (27) and retainer (26) on

angles to the machined gasket

the throttle shaft and lever assembly. Insert assembled

surface and must move freely on the

shaft in carburetor and tap lightly until retainer is flush

float axle shaft.

with casting face.

(2) Install throttle valve (12) on shaft with

(8) Install choke shaft retainer (53, fig. 5-2) and

identification mark on valve facing flange face of

packing (54) in the recess of the choke bracket (52) and

carburetor. Tap valve lightly to center in throttle bore

tap bracket in place on fuel bowl throat to seal packing.

and tighten screws (11) securely.

Secure bracket with screws (50) and lock washers (51).

(3) Install economizer jet (32), idle jet (31) and idle

Install bracket (47) and secure with screws (45) and lock

adjusting needle (14) with spring (15). Turn adjusting

washers (46).

needle (14) all the way in to seat then back off

(9) Install choke shaft (48) and return spring (49).

approximately one turn for preliminary setting.

Install choke valve (43) and spring (44) on lever and

(4) Position a new gasket (30) on float valve seat

center valve in casting before tightening screws (42).

and install float valve and seat (29) into throttle body

(10) Install main nozzle (41) through bottom of

(21).

casting. Place new packing (40) and a gasket (39) in

(5) Install new gasket (22) on throttle body. Install

recess and assemble power jet (38) and nozzle plug (37)

new packing (35) and venturi (36) on throttle body.

into fuel bowl.

(6) Position float (34) on throttle body and install

(11) Invert throttle body (21) and lower fuel bowl

axle shaft (33) through float lever.

(55) over floats. Be sure venturi (36) guides float bodies

(7) Measure distance from float to gasket on

into position.

throttle as shown on figure 5-3. Distance must be 0.250

(12) Install bowl screws (20) and tighten screws

inch (6.35mm) from gasket face to nearest edge of float.

gradually until all screws are secured. Install drain plug

If distance is not correct, use a long nosed pliers to bend

(1) in bottom of bowl.

lever to attain this measurement.

(13) Install levers (7 and 8) on shaft. Install spring

(6) and governor cams (5) over levers (7 and 8). Install

screws (3) and nuts (4 and 2) on governor cams. Install

stop screw (9) and spring (10) on shaft (13).

(14) Install block (18) and screw (19) on choke lever

and secure with washer (17) and clip spring (16).

(15) Install pin (28) and plugs (23, 24, 25 and 55).

b. Installation and Adjustment. Refer to TM 10-

3930-630-12 for installation and adjustments of

carburetor.

5-4