Carburetors consist of a mixer and throttle body assembly, and an optional air horn. Mixers are configured for various modes of operation by using the appropriate replaceable air-gas valve assembly. The shape of the gas valve cone in the air-gas valve assembly determines the mode of operation.
The N-AV1-14-4 (PN N00-7426A) air-gas valve is designed for open-loop LPG (propane) operation and provides the standard air-fuel mixture. Feedback (closed loop) LPG operation and other fuels (eg, natural gas, digester gas, etc) require the use of other air-gas valves. The fuel mixture may leaned with the use of one or more air valve spacer shim ring N-R1-29.