tion of the nozzle and enters the idle passage. The fuel flow is metered by the idle restriction and then passes the idle air bleed where air is added to the fuel. The emulsion of fuel and air continues up the passage past the idle transfer hole which acts as another air bleed when the throttle plate is closed at idle. The fuel then flows through a short horizontal passage to the idle adjusting needle orifice and is discharged at the idle discharge hole. The idle adjusting needle controls the mixture discharged at idle only.

b. During off-idle operation, the idle system functions the same except that fuel is also discharged from the idle transfer hole when the throttle plate is moved past it. The flow from the idle system tapers off as the main metering system begins to operate with increased throttle openings. This provides a smooth transition from idle to cruising speeds.

4.   POWER ENRICHMENT SYSTEM

The added fuel for high power operation is delivered by the power enrichment system.

A vacuum passage in the upper body transmits manifold vacuum to the piston in the vacuum chamber. At idle and cruising speeds, the vacuum is strong enough to hold the piston up in the chamber against the compressed load of the spring. When high power demands reduce the vacuum beyond a predetermined point, the spring expands to force the piston and stem assembly down. This depresses the pin in the center of the power valve, opening the valve. Fuel from the float chamber enters the well above the power valve through a hole in the wall. When the valve is open, this fuel passes through the center of the valve and out calibrated holes in its side which meter the fuel. The fuel then flows through an "L"shaped passage to the main well where it joins the fuel flow of the main metering system, enriching the mixture for full power.

5.   ACCELERATING PUMP SYSTEM The airflow through the carburetor responds almost immediately to any increase in throttle opening, but there is a brief interval before the fuel in the narrow