The Holley Carburetor Model 2140 is equipped with four basic fuel metering systems. They are the main metering system, the idle system, the power enrichment system, and the accelerating pump system. These systems are calibrated to provide an efficient mixture during all phases of engine operation. In addition to those basic systems, there is a secondary system. This system increases the capacity of the carburetor to meet increases in the engine's fuel-air requirements.