Carburetor: Description and Operation

Fig. 1 Holley model 4180-C 4 barrel carburetor exploded view. 1984 V8-460 engine shown, other 1982 - 84 models similar:

Fig. 2 Holley model 4180-C 4 barrel carburetor exploded view. 1986 V8-460 engine shown, other 1985 - 86 models similar:

Fig. 3 Holley model 4180-C 4 barrel carburetor exploded view. 1987 models similar:

The Holley Model 4180-C, Figs. 1 through 3, is a four barrel downdraft two-stage carburetor. This unit can be considered as two dual carburetors, one which supplies an air/fuel mixture throughout the entire engine operating range (primary stage), and the other which functions only when a greater quantity of air/fuel mixture is needed (secondary stage).
The primary stage contains a fuel bowl, metering body and accelerating pump assembly. Each primary barrel contains a primary and booster venturi, throttle plate, main fuel discharge nozzle and idle fuel passage.
The secondary stage contains a fuel bowl, metering body and secondary throttle operating diaphragm assembly. The secondary barrels each contain a primary and booster venturi, throttle plate, idle fuel passages, main secondary fuel discharge nozzle and a transfer system fuel passage from the primary fuel bowl.
A constant fuel supply is provided to fuel metering systems by a fuel inlet system for both primary and secondary stages.