Fig. 34. Sunderman Carburetor
Fig. 34 shows a through section of the new “Nitro”-Sunderman carburetor. This is practically a new model presented to the automobile industry for 1919 and 1920. It is claimed that it is an exact fulfillment of the long sought method of accurate compensation. It is of the single plain tube design with a single gasoline nozzle in the shape of a mushroom placed in the center of the air passage. Around this nozzle, however, rests the floating venturi which is a large end and small center floating air tube seen in Fig. 35 which hurries the air at low speeds and checks the rush at high velocities. Fig. 35 shows the commencement of action at idling speeds, and as the gasoline for idling comes from the same nozzle which furnishes the maximum power, an air by-pass is provided to reduce the suction on the nozzle at low speeds. The one single adjustment on this type of carburetor is shown at (X) in Fig. 36, and is used only to control the passage of air through the by-pass at idling or low speeds. In Fig. 34 the engine’s demand has increased to a point where the suction is greater than the weight of the venturi, which causes it to rise on the air stream, and open up the air passage around the head of the nozzle. This allows the compensation for the correct ratios of the air and gasoline mixtures.
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
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.
Fig. 38. Schebler Model R Carburetor Assembled
Model R Adjustment.—To adjust this carburetor turn the air valve cap to the right until it stops, then to the left one complete turn, start the motor with the throttle 1⁄4 open; after it is warmed up turn the air valve cap to the left until the motor hits perfectly. Advance throttle 3⁄4 on quadrant. If the engine backfires turn screw (F) up, increasing the tension on the air spring until acceleration is satisfactory.