carburetor

Carburetors or carbs for short, have been a way of controlling fueling of engines from the beginning and are still used today in racing such as nascar. The simplicity and ease of tuning is still a favorite of many racing sanctions that dont want to worry about traction control and various other forms of trickery from being hidden inside fuel control boxes. Carbs work off the venturi affect, while the engine is running it is moving air out of the exhaust. On the intake side the engine developes a vacuum. As the air rushes in the carb the diameter of the air opening gets smaller in the middle of the carb. The fuel outlets will be located at the smallest diameter called the venturi. The air coming in the engine must accelerate as it passes through the venturi, trying to fill the vacuum in the intake manifold. The venturi is where the fuel will expel, due to the vacuum being created by the acceleration of the air. The jets, which control the fuel flow are located upstream of the outlets. Most carbs have a low rpm circuit and a high rpm jets called pilot or idle jets and main jets. Like everything in an engine if the carb flows more air it has the ability to make a huge difference in power. Some stock carbs such as carter, webber and quadrajet were a little more complex due to the car manufacturer having to have precise fuel control for emissions compliance. Most racing sanctions such as nascar and nhra use holly carbs for their simplistic nature to tune.