What part of the carburetor increases air velocity and reduces air pressure?

The Venturi is the part of the carburetor that plays a crucial role in increasing air velocity and reducing air pressure. It operates based on the principles of fluid dynamics, specifically the Bernoulli's principle. When air travels through the Venturi, which is a narrowed section of the carburetor, the cross-sectional area decreases. This constriction causes the speed of the air to increase as it moves through the narrower passage.

As the air velocity rises, the pressure within this section drops due to the increase in kinetic energy. This reduced pressure helps to draw fuel from the float chamber or fuel bowl into the airstream, creating a proper air-fuel mixture that is essential for engine combustion. This is fundamental to the carburetor's function in the engine, as it enables optimal performance by ensuring that the right amount of fuel is mixed with air before entering the combustion chamber.

The other components mentioned, like the float, throttle, and choke plate, serve different purposes in regulating fuel delivery and engine performance but do not specifically focus on the increase in air velocity and decrease in pressure, which is the primary function of the Venturi.