Carburation

Carburation, or carburetion, is the process by which a fuel is mixed with air for combustion in an internal combustion engine. A carburetor (carburettor) uses the flow of incoming air to regulate the amount of fuel drawn into the stream, aiming to achieve the desired air-fuel ratio for efficient ignition.

Most conventional carburetors employ a venturi: as air speeds up through a constricted section, pressure drops and fuel is drawn through jets from a float chamber. The throttle valve controls the amount of air entering the engine, while a choke enriches the mixture during cold starts. Additional devices adjust temperature, altitude, and engine load.

Carburetors vary—float-type, pressure-type, and multi-barrel designs—often using fixed jets and mechanical linkages to match throttle position. Some designs rely on acceleration pumps and emulsifying chambers to improve response at load changes.

Carburation was developed in the late 19th and early 20th centuries and became standard in most gasoline-powered vehicles for much of the 20th century. With advances in electronic fuel injection and emissions controls, carburetors have been largely supplanted in modern automobiles, though they remain common in small engines.

Carburation can be sensitive to altitude, temperature, and fuel volatility and may experience icing, leading to symptoms like rough running. Maintenance includes cleaning fuel jets, inspecting seals, and ensuring correct float level; improper tuning can cause inefficient combustion and higher emissions.