1942 - 1947 Chevrolet Shop Manual



6-39

7. Loosen the three screws attaching the air horn to the carburetor body. Remove the main nozzle passage plug. Remove the main nozzle screw plug. Then, using a screwdriver, reach down through the air horn and press on the "D" section of the main nozzle—this will force the main nozzle out of the "D" section in the primary venturi. CAUTION—Do not press on the end of the main nozzle. Remove the air horn screws and air horn. S. Remove the low speed jet. 9. Remove the passage plug and screen for the accelerating pump check valves. Then remove the inlet and outlet valves. 10. Remove the passage plug for the accelerating pump jet, then remove the jet. 11. Remove the idle adjusting screw and the idle port passage plug. In most cases it will not be necessary to remove the choke valve or throttle valve, however check the operation of the choke mechanism. If necessary it may be disassembled by removing the two screws attaching the choke valve. The choke lever and spring may be removed by first removing the snap ring retaining the lever to the boss on the air horn. Inspection 1. Wash all parts thoroughly in clean gasoline or cleaning solvent. 2. Check the idle ports and first by-pass for carbon deposits. Then blow out all drilled passages with compressed air in the opposite direction to that of normal flow of air or gasoline. 3. Inspect the main nozzle for burrs on the venturi end. Blow out the low speed jet and make sure the metering hole in the jet is clean. 4. Check the operation of both the inlet and outlet check valves. Inspect the accelerating pump jet to make sure it is clean. 5. Inspect the accelerating pump plunger. If the leather or its expanding spring are damaged in any way, the plunger assembly should be replaced. 6. Inspect the metering rod jet and metering rod for wear or damage and to make sure it is the correct metering rod for the carburetor. Reassembly 1. If the throttle valve was removed care must be used to make sure the letter "C" stamped on the valve is toward the idle port when reassembling, Fig. 80. 2. If the choke valve has been removed, it must be assembled to the shaft with the letter "C" stamped on the valve toward top of air horn.
	Fig. 80—Correct Assembly of Throttle Valve 3. Assemble the air horn loosely to the carburetor body, making sure the small gasket is in place at the balance passage.
	4. Assemble the copper gasket on the main nozzle, (4) Fig. 82, Hold the carburetor with the air horn down, line up the "D" section on the end of the nozzle with the "D" opening in the primary venturi and drop the nozzle (5) into the opening. Install the nozzle screw plug (3) and
	tighten it securely.
	Tighten the three	Fig. 81— Checking Seat on Low Speed Jet
	air horn screws. Install the main nozzle passage plug (1) using a new copper gasket (2). 5. Install the low speed jet (13) and gasket (12), in the carburetor body, tighten in place, then again remove the jet and check the bearing on the top end. If there is a complete bearing around the top of the jet indicating a full seat, it may be reinstalled, Fig. 81. If the bearing is incomplete a new jet should be installed.