Replace damaged parts only after completing all tests.

Replace damaged parts only after completing all tests.

Figure 3-61. Removing Main Nozzle Welch Plug
Figure 3-62. Removing Main Nozzle
Figure 3-63. Installing Main Nozzle

8. Remove plastic diaphragm cover. Inspect accelerator pump leather for fold over or coil spring out of correct position.

Check accelerator pump outlet ball check valve to see that ball is free.

Inspect gasket and diaphragm for distortion or misplacement on carburetor body. Diaphragm must not be stretched or have a rippled appearance particularly within the valley portion which should be uniform in shape. (Gasket should be assembled next to body.)

Lightly make attempt to rotate metal diaphragm washer, riveted to upper side of diaphragm. If diaphragm plate rotates freely with no drag, replace diaphragm assembly. Diaphragm plate should not be loose.

Prior to removal of the inlet lever the initial needle seat leakage test should be performed 10 to 12 times with the bulb tester, as follows: Close bulb valve. Apply pressure to the inlet, sealing the vent fitting. Open bulb valve and again apply pressure. This repetition checks the sealing of the needle in the seat ensuring that it is not sticking open at lever pin or at groove in needle.

9. Inspect inlet needle lever for correct adjustment. It should be flush with surrounding floor of carburetor body. If not equipped with shackled needle, replace with Kit No. 27588-66. Tighten seat to 45 in-lbs torque. See Figure 3-64.

Figure 3-64

10. Test economizer ball check for leakage and correct operations as follows:

Using hose end of tool. Part No. 96960-68 place it over economizer welch plug hole so it seals off surrounding area. With alternate pressure and vacuum applied with mouth, as shown in Figure 3-65, ball check should release and seal. Replace any defective parts.

After plastic cover has been removed, remove welch pi ug at idle adjuster, all gaskets, diaphragms, needle and seat, and high speed nozzle before cleaning carburetor in a caustic carburetor cleaner, since the caustic cleaner will damage gasket material and the highspeed nozzle plastic check ball. Only gaskets which are in perfect condition should be reused. The metal parts may also be cleaned in lacquer thinner with a small brush and blown dry.

Inspect by attempting to rotate, or move all welch plugs in body. A close inspection of wall area around welch plugs can disclose a leaking condition. Whenever a welch plug is removed, a new one should be reinstalled. If leakage is suspected due to rough or damaged welch plug seat in casting, apply a small amount of seal-all to edge of welch plug after installing it in recess.

After carburetor has been reassembled, recheck accelerator pump per item 1 under "Tests."

After carburetor has been reassembled, recheck accelerator pump per item 1 under "Tests."

Figure 3-65. Checking Economizer Bali Check Valve for Leakage


Remove idle (26) and intermediate (38) fuel adjustments.

Remove two throttle shutter screws (52) and the throttle shutter (51). The sides of the shutter are tapered 15° to conform to the throttle bore. Observe the direction of this taper and the position of the shutter so that it can be reassembled later in the correct position.

Remove the accelerating pump lever retaining screw (3) and pull the throttle shaft assembly (46) out of the carburetor body. Remove compression spring (50), washers (49), and shaft dust seals (48).

Remove six screws and washers (22) and the body cover <18).

Remove accelerating pump plunger assembly (1). Remove channel plug screw (21). Remove metering diaphragm (17).

Remove metering diaphragm gasket (23). Note that the gasket is assembled next to the body casting.

Remove fulcrum pin retaining screw (34), fulcrum pin (33), inlet control lever (32), and metering spring (37).

Remove the inlet needle (32).

Remove the inlet seat and cage assembly (35), using a 3/8 in. thin wall hex socket wrench. Note the position of the inlet seat insert with the contoured side toward the outside of the cage and the smooth side toward the inside of the cage.

Remove the inlet seat gasket (36), using a small tap or bent wire.

Remove plug screw (44).

Remove fixed main jet (42) and gasket (43).

Remove main nozzle welch plug (6) by drilling 1/8 in. diameter hole off center and just breaking through the welch plug. Do not drill deeper than the welch plug because this would probably damage the nozzle assembly. Pry out the welch plug with a small punch, being careful not to damage the casting counterbore edges around the plug.

Remove idle port welch plug (6), using the same procedure described above.

Remove welch plug (8) and economizer check ball (24). Pry out the welch plug carefully, using a small punch.

Remove two choke shutter screws (16) and the bottom half of the choke shutter (15).

Pull the choke shaft assembly (13) out of the body. This will release the top half of the choke shutter (11), the spring (12), the choke friction ball (9), and friction ball spring (10).

Remove the choke shaft dust seal (14).


The carburetor body can be cleaned in commercial carburetor solvent such as Hydroseal to remove varnish from the channels and metering chamber.

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