This carburetor can be cleaned or repaired without the use of special tools.
Before making any adjustments to the carburetor, it is important that the breaker points and spark plugs be properly spaced, the ignition timing correct and valve tappets set to proper clearance. Check all carburetor assembly screws and manifold flange bolts, see that they are thoroughly tightened and that there are no leaks at gaskets. All of these instructions are explained in the vehicle manufacturer’s maintenance manual.
Proper carburetor performance is dependent on maintaining the correct fuel level in the bowl. When checking the fuel level in an open vessel, under 3PSI, the level should be measured below the surface of the float chamber cover with the gasket in place (distance 22 in figure below). The level may be corrected by bending float arm (11).
Always refer to proper specification sheed for correct level.
The float level can be set accurately, when the air horn is off, by gauging the distance between the bottom of the float and the flange surface of the air horn. Holding the air horn upside down and with the float in the closed position, measure the distance from the flange surface of the air horn to what would normally be the bottom side of the float (distance 23, figure A). The correct distance that it should measure is indicated on the proper specification sheet. To correct the float setting, the float lever arm (11) should be bent up or down to bring the float within the established limites and thus correct the fuel level for best operation. Pushing the float toward the float chamber cover raises the level, away from the cover lowers the level.
NOTE: The fuel inlet valve, valve seat, and gasket are services an an assembly and should be used as supplied in factory matched sets. When replacing the valve seat be sure to use a screwdriver with a blade wide and heavy enough to fill the slows in a valve seat.
First set the idling speed by adjusting the throttle stop screw (36). The idle mixture is controlled by the idle adjusting needle (4).
NOTE: These needles regulate fuel flow and are not air bleed needles. Turning these screws in (or to the right) makes the mixture leaner and turning them out (or to the left) makes the mixture richer. Screws should be turned in until they just touch the seat, then backed off one full turn. Care should be taken not to jam the screws against the seat tight enough to groove the points. If this ocurs, the needles will have to be replaced before a satisfactory adjustment can be made. The screws should be adjusted with the fingers to avoid damage.
When the engine has warmed up, turn both idle screws out until the engine starts to slow down. A point half way between these two will be very close to the correct idle mixture. After arriving at the correct mixture, it may be necessary to reset the throttle stop screw to obtain the correct idle speed. Changing the speed may make a slight change in the idling mixture. In the event this occurs, re-adjust the screws as outlined above.
NOTE: When adjusting the idle mixture, it is important that both idle screws be set at approximately the same number of turns open, otherwise, the off idle performance may be erratic.