Long before electronic fuel injection ruled the world, the job of mixing air and fuel was done by a clever mechanical device called a carburetor. In its simplest form, the carburetor mixes varying amounts of air and fuel and delivers the mixture to the engine for combustion in the cylinders through the intake valves as required.
The carburetor—without the aid of numerous sensors and computers—has to create the correct mixture because having too much or too little air and fuel won’t do the engine any good. Too much air and inadequate fuel results in a “lean” mixture, which negatively affects engine performance. Too much fuel mixed with too little air, on the other hand, brings about a “rich” mixture, causing the engine to waste fuel, run poorly, or worse, not run at all.
How a Carburetor Works
The carburetor has a very complex job of adjusting the air/fuel mixture to match engine requirements based on driver throttle input, temperature, engine load, altitude, etc. As air flows through the carburetor, it passes through a narrow section called the venturi, where it speeds up and loses pressure. As the air pressure falls, a vortex effect is formed, drawing gasoline from the jet, which is a small tube adjacent or near venturi.
The air-and-fuel mixture then passes the throttle plate, which moves to open or close to control the amount of air and fuel flowing to the cylinders. This plate moves in conjunction with the accelerator pedal.
Higher performance and many racing vehicles are equipped with more complex systems with multiple carburetors, several venturis or carburetors with multiple throttle bodies to provide more mixture in the upper RPM ranges.
Types of Carburetor
There are many types of carburetors to meet the needs of any internal combustion engine. From a one barrel motorcycle carb to a huge Holley four barrel 750 cfm double pumper, brilliant engineers design the perfect fuel mixing system for the needs of the engine and its operating range.
How to Clean a Carburetor
The best way to maintain a carburetor is through regular use; take your car out for a 20 minute drive to allow all systems to warm up and operate as designed. Letting your vehicle sit for long periods of time will dry out seals, seize linkages, gum up pumps and filters and otherwise make your driving experience less than optimal. In addition, running high quality fuels will ensure fewer deposits in your fuel system from gas tank to combustion chamber and all the components in between.
As the popularity of fuel injection systems continues to grow, the carburetor still captures the hearts of performance enthusiasts and vintage car owners who yearn to see throttle linkages moving, hear and see the jets squirting fuel and love to tinker and tweak to hit that perfect air-fuel mixture.
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