Metering Rod

A metering rod varies the size of the carburetor jet opening. Fuel from the float bowl is metered through the jet and the metering rod within it. The fuel is forced from the jet to the nozzle extending into the venturi. As the throttle valve is opened, its linkage raises the metering rod from the jet. The rod has several steps, or tapers, on the lower end. As it is raised in the jet, it makes the opening of the jet greater in size. This allows more fuel to flow through the jet to the discharge nozzle. The metering must keep pace with the slightest change in the throttle valve position so that the correct air-fuel mixture is obtained in spite of engine speed.