I am only going to print a small portion of the info I can email you It includes the Model TSX Carburetor, Marvel-Schebler Carburetor and zenith 61 & 161 these are very similar to what you have it includes repair procedures and parts list. If you want a copy Its 20 pages no charge to anyone email me @
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ZENITH 61 AND 161 SERIES CARBURETORS
Fig. S-22
The Zenith 61 and 161 Series carburetors are
of updraft single venturi design. They are made
in 5/8" and %$" S.A.E. barrel sizes; with 5/8 ", 7/8",
1" and 1 14" S.A.E. flange sizes available. They
are made with selective fuel inlet, with or without
a back suction economizer and a main jet
adjustment.
They are "balanced" and "sealed," and the
semi - concentric fuel bowl allows operation to
quite extreme angles without flooding or starving.
This design makes them particularly adaptable to
smaller farm tractors and a great variety of
agricultural machines and industrial units.
MODEL DESIGNATION
Type—Updraft.
Material—Barrel and bowl castings, cast iron.
Styles—"A" Throttle and choke shafts parallel.
"D" Equipped with degasser assembly.
"E" Elbow air intake.
"J" Back-suction economizer.
"R" Built-in governor.
"S" Straight through air intake.
"X" Flange next size larger than standard.
"XX" Flange second size larger than
standard.
Size
Designation
Nominal
Size
Throttle Bore
Diameter
Flange Size
S.A.E. Standard
5 5/8" .787 or Ii"
7 /8" 1.023 or 1A" 7/8"
X7 7/8" 1.023 or 11;2" 1"
XX7 7/8" 1.023 or 1A" 11/4"
8 1" 1.181 or 1A" 1"
FUEL SUPPLY SYSTEM
The fuel supply system is made up of the
threaded fuel inlet, the fuel valve seat, fuel valve,
float and fuel bowl.
The fuel supply line is connected to the threaded
inlet. The fuel travels through the fuel valve
seat and passes around the fuel valve and into the
fuel bowl. The level of the fuel in the fuel
chamber is regulated by the float through its
control of the fuel valve. The fuel valve does not
open and close alternately but assumes an opening,
regulated by the float, sufficient to maintain
a proper level in the fuel chamber equal to the
FUEL SUPPLY SYSTEM
Fig. S-23
demand of the engine according to its speed and
load.
The inside bowl vent as illustrated by the passage
originating in the air intake and continuing
through to the fuel bowl, is a method of venting
the fuel bowl to maintain proper air fuel mixtures
even though the air cleaner may become restricted.
This balancing is frequently referred to
as an "inside bowl vent."
IDLE SYSTEM
The idle system consists of the idle discharge
port, idle air passage, idle adjusting needle, idle
jet, and fuel passage.
The fuel for idle is supplied through the main
jet to a well directly below the main discharge
jet. The pick-up passage is connected to this
well by a restricted drilling at the bottom of this
passage. The fuel travels through this channel
to the idle jet calibration. The air for the idle
mixture originates back of (or from behind) the
main venturi. The position of the idle adjusting
needle in this passage controls the suction on the
idle jet and thereby the idle mixture. Turning
the needle in closer to its seat results in a greater
suction with a smaller amount of air and therefore
a richer mixture. Turning the needle out
away from its seat increases the amount of air
IDLE SYSTEM
Fig. S- 24
and reduces the suction. and a leaner mixture is
delivered. The fuel is atomized and mixed with
the air in the passage leading to the discharge
port (or priming plug) and enters the air stream
at this point.
HIGH SPEED SYSTEM
The high speed system controls the fuel mixture
at part throttle speeds and at wide open
throttle. This system consists of a venturi, controlling
the maximum volume of air admitted into
the engine; the main jet, which regulates the
flow of fuel from the float chamber to the main
discharge jet ; the well vent, which maintains
uniform mixture ratio under changing suction
and engine speeds; and a main discharge jet,
which delivers the fuel into the air stream.
The main jet controls the fuel delivery during
the part throttle range from about one-quarter
HIGH SPEED SYSTEM
Fig. S-25
to full throttle opening. To maintain a proper
mixture ratio a small amount of air is admitted
through the well vent into the discharge jet
through the air bleed holes in the discharge jet
at a point below the level of fuel in the metering
well.
The passage of fuel through the high speed
system is not a complicated process. The fuel
flows from the fuel chamber through the main
jet and into the main discharge jet where it is
mixed with air admitted by the well vent, and
the air-fuel mixture is then discharged into the
air stream of the carburetor.
BACK SUCTION ECONOMIZER SYSTEM
Fig. S- 26
ECONOMIZER SYSTEM
The economizer system consists of a "milled"
slot in the throttle shaft, which acts as a valve
to open or close the system ; a vacuum passage
from the throttle bore to the slot in the throttle
SECTION 5, FUEL SYSTEM
shaft; and a vacuum passage from the slot in the
throttle shaft to the fuel bowl.
This system allows economical fuel mixture
ratios for part throttle operation while still permitting
the richer mixture ratios that are needed
for full load operation.
The economizer system performs its function
by establishing a "back suction" on the fuel in
the fuel bowl during most of the part throttle
range of operation. This "back suction" is created
by manifold vacuum, through the channels connecting
the throttle bore with the fuel bowl. This
retards the flow of fuel through the metering
systems and thus permits the carburetor to operate
on leaner part throttle mixture ratios.
The rotation of the throttle shaft controls the
economizer system. During part throttle operation
from about one-quarter to three-quarters
throttle, the passages are open and the pressure
in the fuel bowl is lowered. This retards the flow
through the main jet and a leaner mixture is
supplied. pn full throttle opening the passages
are closed and the main jet flows to full capacity
to supply the richer mixture required.
CHOKE SYSTEM
The choke system consists of a valve mounted
on a shaft located in the air entrance and operated
externally by a lever mounted on the shaft.
The choke valve is used to restrict the air entering
the carburetor. This increases the suction on
CHOKE SYSTEM
Fig. S-27
the jets when starting the engine. The choke
valve is of a "semi-automatic" type, having a
poppet valve incorporated in its design, which is
controlled by a spring.
The poppet valve opens automatically when the
engine starts and admits air to avoid over-choking
or flooding of the engine. The mixture required
for starting is considerably richer than that
needed to develop power at normal temperatures.
As the engine fires and speed and suction are increased,
the mixture ratio must be rapidly reduced.
This change is accomplished through adjustment
of the choke valve and the automatic
opening of the poppet valve to admit more air
when the engine fires.