Carter Carburetor: Diagram, and Working Principle.

The Carter carburetor diagram is similar to the Zenith carburetor. It consists of many circuits and internal parts. Here is the carter carburetor diagram and full details- 

Carter carburetor- 

Carter Carburetor Company was established in 1909 and closed operation in 1985. It was founded by William Carter, who is an automotive engineer, starting experimental things on carburetors while running a successful bicycle shop.

Carter carburetor diagram- 

Carter carburetor diagram.
Carter carburetor diagram.


The Carter carburetor is a down draught type carburetor. It consists of many circuits- float circuit, starting circuit, Idle, and low-speed circuit, part throttle circuit, Full throttle circuit, and Acceleration pump circuit. This carburetor has similar parts to other carburetors, like a throttle valve, accelerator linkages, and venturi portion. In the next, I will discuss the working of this Carter carburetor.

Carter carburetor working- 

The Carter carburetor was widely used in American cars. It was invented by William Carter in 1909 and was one of the first carburetors to use a downdraft design, which allowed for better fuel distribution and improved engine performance. Carter carburetor was known for its reliability and durability. 
Carter carburetor.
Carter carburetor. Source-Wikipedia


Carter carburetors were used on a wide range of vehicles, from small cars to large trucks and even some aircraft. However, with the advent of electronic fuel injection in the 1980s, carburetors like the Carter became less common and were eventually phased out in favor of more advanced fuel delivery systems.
As shown in the diagram- the carter carburetor achieves an air-fuel mixture through a series of components and mechanisms that work together to regulate the flow of air and fuel. As the air enters the carburetor through an air cleaner and passes through a venturi tube, which narrows and speeds up the airflow. The increased speed of the air creates a low-pressure area at the narrowest point of the venturi, which draws fuel from the carburetor’s float bowl. This is done through the vacuum created by this passage. The fuel flows through a series of jets and tubes, which control the amount of fuel entering the venturi tube.



The throttle plate, controls the amount of air entering the carburetor and regulates the engine’s speed. The throttle plate was operated by the driver. As per acceleration, and deceleration, the throttle plate opens as per it. The air and fuel mix in the venturi tube and create a combustible mixture(stoichiometric ratio), which is then delivered to the engine’s combustion chamber through the intake manifold.


Circuits in the Carter carburetor- 

The Carter carburetor consists of the following circuits- 

Float circuit- 

The foot circuit controls the supply of fuel from the fuel filter into the float chamber. The float is pivoted at the side of the chamber and operates a needle valve to close and open the passage through which the fuel enters the chamber. 

Starting circuit – 

At the time of starting the cold engine, the choke valve is operated to close the air supply. The choke valve is mounted eccentrically, due to which it opens automatically after the engine has started. The whole suction is applied on the main nozzle which delivers fuel. The air supply is quite small, and the air-fuel mixture becomes rich for starting. 

Idle and low-speed circuit- 

A rich mixture is required in small quantities for idling. The throttle valve is almost closed during the idling, thus the engine suction is applied at the idle port which supplies the required air-fuel mixture. For low speed, the throttle valve is a little open. The main nozzle also begins to supply the fuel. 

Part throttle circuit- 

The throttle valve is further opened to increase the speed. At this stage, the throttle valve is partly opened and the fuel is supplied by the main nozzle only. 

Full throttle circuit-

When the throttle valve is fully opened the maximum amount of air passes through the venturi and a higher rate of fuel supply is required. This is achieved utilizing the metering rod. When the accelerator pedal is depressed, the throttle valve is fully opened, and simultaneously the metering rod is lifted up in the jet providing a larger area for fuel supply. This maximum amount of air-fuel mixture is supplied for high speed. 

Acceleration pump circuit-

An extra amount of fuel is required for acceleration. This is done by an acceleration pump. When acceleration is desired, the acceleration pedal is depressed, it actuates the pump which delivers an extra amount of fuel into the venturi. When the accelerator pedal is released, the piston moves up and sucks petrol from the float chamber. The pump is now ready for the next operation.

Differences between the Carter carburetor and solex carburetor- 

SL- no Carter carburetor Solex carburetor
01 Carter carburetor was made in the United States. The solex carburetor was made in France.
02 Carter carburetor uses a downdraft design. Solex carburetor uses a side-draft design.
03 The Carter carburetor has a fixed venturi tube. Solex carburetor has a variable venturi tube.
04 The Carter carburetor has fixed jets. The Solex carburetors have adjustable jets.
05 The carter carburetor uses a mechanical fuel pump. The solex carburetor is capable to use both mechanical and electrical fuel pumps.
06 The Carter Carburetor has an accelerator pump, which delivers extra fuel when the throttle is opened quickly. While the Solex Carburetor does not.
07 The Carter Carburetor has a manual choke. The Solex carburetor has a manual and automatic choke.
08 The Carter Carburetor is made of metal. The Solex carburetor is made of a combination of metal and plastic.
09 The Carter Carburetor was mainly used in American-made vehicles. The Solex Carburetor was used in European-made vehicles.
10 Carter Carburetors are no longer in production. Solex Carburetors are still being manufactured for some applications.
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