Fig. 35. Sunderman Carburetor
In [Fig. 37] the venturi closes the air by-pass and under full suction, gives the maximum area around the nozzle for leaner mixtures and full volumetric. The unrestricted air passage in the plain tube type of carburetor is here worked out to its fullest development.
Fig. 36. Sunderman Carburetor
The Venturi.—This is a stream line air passage tapered to a narrow throat near the center which increases the velocities without offering a restriction to the free air passage, and being of a very loose fit in the carburetor, is allowed to float up and down on the air stream around the nozzle over which it automatically centers at all times. The venturi goes into action slowly as it is retarded by the action of the air by-pass, but rises fast when the latter is cut off. It rides on the air stream at a perfect balance and offers no resistance to the air passage because of its stream line taper, and as the venturi float is sensitive to a fine degree, it is ready for any change in the motor suction and compensates accordingly. The jet tube running up into the mushroom head contains a jet which is drilled for the particular requirements of the motor on which the carburetor is installed. This jet feeds into the mushroom head which is drilled with four small holes which spread the gasoline by capillary action in a fine fan film to all sides of the under surfaces of the slot. Here the ascending air picks it off at right angles to its path in a very fine vapor. This vapor is carried up the stream line venturi without cross currents and is in a finely mixed state of flame-propagation. The heavier fuels are readily broken up with this nozzle and straight kerosene has been used with success. This carburetor does not require any other care than a thorough cleaning out once or twice in a season.
Fig. 37. Sunderman Carburetor
THE SCHEBLER MODEL “R” CARBURETOR
[Fig. 38] shows a section view of operation and adjustment on the model “R” Schebler carburetor. This carburetor is designed for use on both four and six cylindered motors. It is of the single jet raised needle type, automatic in action, the air valve controlling the needle valve through a leverage arrangement. This leverage attachment automatically proportions the amount of gasoline and air mixture at all speeds. This type of carburetor has but two adjustments. The low speed adjustment which is made by turning the air valve cap and an adjustment on the air valve spring for changing its tension. (A) shows the air valve adjusting cap. (B) is the dash control leverage attachment. (C) is the air valve and jet valve connection. (D) is the boss that raises the jet valve needle and lowers the spring tension on the air valve giving a rich mixture in starting. The needle valve seats in E and controls the nozzle spray. (F) is the air valve spring tension adjusting screw.
