[Figure 2-11]  This chamber provides a nearly constant level  of fuel to the main discharge nozzle which is usually about  1 ⁄ 8" below the holes in the main discharge nozzle. The fuel  level must be maintained slightly below the discharge nozzle  outlet holes to provide the correct amount of fuel flow and  to prevent fuel leakage from the nozzle when the engine is  not operating. will not adhere to the inlet screen or walls or affect engine  airflow or manifold pressure. This ice may enter the carburetor  and gradually build up internally in the carburetor air metering  passages and affect carburetor metering characteristics.  A float-type carburetor consists essentially of six subsystems  that control the quantity of fuel discharged in relation to the  flow of air delivered to the engine cylinders. These systems  work together to provide the engine with the correct fuel flow  during all engine operating ranges. The level of fuel in the float chamber is kept nearly constant by  means of a float-operated needle valve and a seat. The needle  seat is usually made of bronze. The needle valve is constructed  The essential subsystems of a float-type carburetor are  illustrated in  Figure 2-10 . These systems are: A float chamber is provided between the fuel supply and the  main metering system of the carburetor. The float chamber,  or bowl, serves as a reservoir for fuel in the carburetor.  2-10 Figure 2-10.  A float-type carburetor. Figure 2-11.  Float chamber (bowl) with float removed. Float-Type Carburetors 1.  Float chamber mechanism system 2.  Main metering system 3.  Idling system 4.  Mixture control system 5.  Accelerating system 6.  Economizer system Float Chamber Mechanism System From fuel pump Throttle Metering jet Discharge nozzle Main air bleed Float chamber