“NITRO”-SUNDERMAN CARBURETOR
[Illustration: 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.
[Illustration: 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.
[Illustration: 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.
[Illustration: 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.
[Illustration: 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.