Fig. 9 - Turn Signal Mechanism

Fuel and Exhaust

Six Cylinder Carburetor

Calibration changes are made to meet new engine requirements. The inlet filter element is new, with larger area and particle retention size reduced from 125 to 60 micron. This same filter will be used on all V-8 passenger cars and light duty trucks replacing the percent AC sediment bowl type. We recommend the element be replaced every 15000 miles, or before if flooding occurs. The element may be cleaned by washing in a solvent and blowing out.

Eight Cylinder Carburetors

The choke heat baffle (in the exhaust manifold heat tube) is no longer used on any 283 engines. A choke heat baffle is added to the choke heat tube on the 348 engine 3x2 carburetor exhaust manifold.

Rochester 2GC

The air horn is revised to incorporate a side inlet with an integral fuel filter

A new float assembly requires a new float setting gage. This change is carried over into all 1959 two barrel passenger car and truck carburetors.

On the model 2GC carburetor for factory-equipped air conditioned cars, an idle compensator is used as an additional aid to prevent stalling during prolonged hot idle periods (Fig. 10). This is simply a thermostatic controlled air bleed which supplies additional idle air to the idle mixture.

Fig. 10 - 2GC Carburetor Idle Compensator (used with Air Conditioning)

The idle compensator consists of a bimetal strip, a valve, and a mounting bracket. It is mounted on the rear of the carburetor bowl between the two large venturis. The valve is completely enclosed in a cavity in the bowl casting and has a protective cover and gasket held in place by mounting screws. The valve itself seats on a hole which is connected by an air passage to a point below the throttle valves.

In operation, when idling hot for long periods, the bi-metal strip will expand outward, forcing the compensator valve off its seat. This allows additional air, supplied from inside the carburetor bore above the large venturis, to by-pass the compensator valve and be added at a point below the throttle valves, offsetting the enriching effects of high engine temperatures.

When underhood temperatures decrease, the compensator valve closes and idle operation returns to normal.

The idle compensator valve must be held closed when making the engine idle adjustment. No servicing other than replacement is suggested. Do not attempt to adjust this valve.

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