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Understanding Zenith Carburetor

Zenith Carburetor (later the Bendix Corporation’s Fuel Devices Division) was a manufacturer of gasoline engine management systems and components, primarily carburetors, and filters, in the United States. It is a well-known British carburetor that is utilized by a number of well-known companies. Zenith Carburetor Company was founded in 1910. There is no starting problem with this carburetor, and it also offers a rich mixture at high speeds.

In this article, you’ll learn the definition, parts, diagram, construction, and working of a zenith carburetor.

zenith-carburetor-working

Read more: Different types of carburetor and their functions

What is a zenith carburetor?

Zenith carburetor is an old method of fuel injection in internal combustion engines which has been replaced by fuel injectors. although it has no starting issue and offers a rich mixture at high speed, only that it’s a conventional method of the fuel mixture. Zenith carburetors are found on aircraft and marine engines. They are common on farm tractors and in some commercial vehicles. Zenith company still produces a different model of carburetors today for various applications.

Parts

Zenith carburetors consist of the following parts:

  • Float Chamber
  • Main Line
  • Main Jet
  • Compensating Jet or Auxiliary Jet
  • Starting Jet
  • Reservoir or Auxiliary Chamber
  • Choke
  • Throttle Valve

Diagram of a zenith carburetor:

Zenith-Carburetor

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Construction

The Float Chamber is connected to the Venturi by the Main Line in this carburetor. The primary purpose of the fuel chamber is to draw fuel from the fuel tank. There are two balls, two floats, and a spindle in this fuel chamber. When the throttle is closed, the airflow to the carburetor is restricted. A throttle valve is a valve that connects the carburetor to the engine and opens when the engine requires fuel.

Through the Main Jet, fuel from the mainline is mixed with air to generate an air-fuel combination. Aside from the main jet, there is also a compensating jet that compensates when the engine requires extra fuel at high speeds. The fuel for this compensating jet comes from a reservoir or an auxiliary valve. Aside from the compensating jet, it also has a beginning jet that assists the engine during startup. Fuel can also be obtained via a reservoir or an auxiliary valve.

Working Principle

The working of a zenith carburetor is less complex and can be easily understood. When no fuel is needed, fuel from the fuel tank enters the float chamber through a route that is blocked by a spindle in the float chamber. The fuel supply to the fuel chamber is blocked and unblocked by this spindle, which rotates up and down.
When the fuel flow to the fuel chamber is reduced, the two floats drop, along with the two balls. Because the balls and the spindle are connected like a Seesaw, when the balls fall, the spindle rises, clearing the fuel channel to the fuel chamber.

On the other hand, as the fuel supply in the fuel chamber increases, the two float, and the balls rise as well. Because of the Seesaw link between the balls and the spindle, when the balls rise, the spindle falls. The path is stopped when the spindle falls down, and the fuel supply to the fuel chamber is cut off.

When the engine is at low speed, the choke is opened, and the air travels through the venturi, increasing the velocity of the air while decreasing the pressure. Because the fuel chamber has a high pressure due to air pressure while the venturi has low pressure. As a result, fuel flows from high to low pressure, i.e., from the fuel chamber to the mainline, where it is mixed with air from the Main Jet. This gasoline combines with air from the choke to create a mixture. This mixture has a 15:1 ratio, with 15 being air and 1 being fuel. After going via the throttle valve, which is just slightly opened at low speeds, this mixture reaches the engine.

Read more: Difference between fuel injection and carburetor

Watch the video below to learn more on the working of a zenith carburetor:

When a vehicle travels at a high pace, the engine speed increases, resulting in increased suction. More fuel is delivered by the main jet due to the higher suction at the venturi, and fuel is also supplied by the compensating jet or auxiliary jet. The fuel for this auxiliary jet comes from the auxiliary valve. However, because the fuel stored in the auxiliary valve or reservoir is limited and empty at high speeds, the compensating jet can only supply fuel for a limited time. Because there is an aperture between the reservoir and the fuel chamber, this reservoir takes a long time to store the gasoline. Because of the hole, very little gasoline can travel from the fuel chamber to the reservoir. As a result, at high speeds, fuel is sprayed from both the main and compensating jets for a short period of time.

The throttle valve is virtually closed when the engine is started. At the time of starting, there is a very small space for the fuel to travel through the throttle valve. The engine requires a rich mixture in order to start.
The air from the air filter passes through the gap in the side of the throttle valve, increasing the velocity of the air and decreasing the pressure of the air on the upper side of the throttle valve, resulting in a suction effect at the Starting jet, which is located at the top of the throttle valve. The fuel for this starting jet comes from the same reservoir as the fuel for the compensating jet.

Read more: Understanding Carter Carburetor

Conclusion

Zenith carburetor is an old method of fuel injection in internal combustion engines which has been replaced by fuel injectors. although it has no starting issue and offers a rich mixture at high speed, only that it’s a conventional method of the fuel mixture. That is all for this article, where the definition, parts, diagram, construction, and working of a zenith carburetor are been discussed.

I hope you learn a lot from the reading, if so, kindly share with other students. Thanks for reading, see you around!