CARBURETOR

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INTRODUCTION:
BASIC INFORMATION: The carburetor works on Bernoulli’s principal: the faster air moves, the lower its static pressure, and the higher its dynamic pressure. The throttle (accelerator) linkage does not directly control the flow of liquid fuel. Instead, it actuates carburetor mechanisms which meter the flow of air being pulled into the engine. The speed of this flow, and therefore its pressure, determines the amount of fuel drawn into the airstreams.
When carburetors are used in aircraft with piston engines, special designs and features are needed to prevent fuel starvation during inverted flight. Later engines used an early form of fuel injection known as a pressure carburetor.


How the carburetor basically works?
• A carburetor is that part of a gasoline engine which provides the mixture of gasoline and air that the engine burns. The carburetor must mix the gasoline with about 15 times its weight in air for the engine to run smoothly at all speeds. A driver controls the engine speed by increasing or reduction the flow of the fuel mixture.
• Carburetors are called updraft or downdraft according to their position. If the carburetor is below the intake manifold's input, it is updraft. If it is above, it is a downdraft. The Zenith carburetor, which was used on the Model A, is an updraft.
• The float chamber of the carburetor stores a small amount of gasoline, which is gravity-fed from the Model A fuel tank. When the carburetor bowl chamber is filled to the proper level, a float resting on top of the gasoline closes a valve restricting flow from the tank fuel line. As the engine consumes gasoline, the float drops. This opens the valve and lets more gasoline flow into the bowl chamber.


• Off-idle circuit
As the throttle is opened up slightly from the fully-closed position, the throttle plate uncovers additional fuel delivery holes behind the throttle plate where there is a low pressure area created by the throttle plate blocking air flow; these allow more fuel to flow as well as compensating for the reduced vacuum that occurs when the throttle is opened, thus smoothing the transition to metering fuel flow through the regular open throttle circuit. Main open-throttle circuit