The tapered end of the metering rods fit down into the main jets. When idling, the metering rods are in the down position. As the throttle is opened up, the metering rods are raised up allowing more fuel to pass.
The metering rods must be adjusted after the pump adjustment, or when leaner than standard rods are installed. No gauges are necessary.
With the throttle lever set screw backed out and throttle valves seated in the bores of the carburetor, press down on vacumeter link (D) until metering rods bottom. With rods held in this position, revolve metering rod arm until lip contacts vacumeter link (E). Hold in place and carefully tighten metering rod arm set screw (F).