ABC's of Carburetion



	IMPORTANT ADJUSTMENTS Continued

	ON THE ENGINE

	SLOW IDLE—The slow idle setting is an important factor in smooth idling and stalling after engine warm-up. Therefore, it should be adjusted carefully according to factory specifications with the use of a tachometer and vacuum gauge. AUTOMATIC CHOKE STOVE - Rochester Automatic choke carburetors for Chevrolet application require the use of a choke stove assembly and heat pipe. For proper choke operation, this stove must be properly installed. Install on forward side of exhaust manifold. Do not insulate steel heat pipe. The recommended installation gives best results with factory calibrated parts.	FAST IDLE—The final fast idle adjustment should always be made on the engine with the use of a tachometer. Adjust according to factory specifications. If improperly adjusted, it may result in hard starting when cold, stalling or loading up.


	TOOLS AND SPECIFICATIONS ARE AVAILABLE THROUGH UNITED MOTORS SERVICE

	Since service adjustments on all models of Rochester Carburetors have been kept to a minimum, the number of special tools and gauges required for field service adjustments	are comparatively few. The necessary tools and gauges are available through the facilities of United Motors Service Distributors everywhere.

	CAUTIONS

	1. The practice of indiscriminately installing lean main metering jets to improve economy is without basis. Lean jets are intended for high altitude use only and will not improve mileage at average or sea level altitudes. Excessively lean jets may result in burned engine valves. 2. Mileage complaints should always be verified with a gas-per-mile gauge with the owner driving. Many factors, other than carburetion, affect mileage. 3. As mentioned before, CARBURETION SHOULD ALWAYS BE CHECKED LAST IN ENGINE TUNE-UP. 4. Do not remove throttle valves or shafts	from Rochester Carburetors. All idle drillings are made with relation to a proper fitting valve. Since removing and replacing the valve will change this relationship, rough or erratic idling may be the result. Be certain all carburetor adjustments are made in proper sequence according to factory specifications. Always remember-DIRT IS A CARBURETOR'S WORST ENEMY. A good cleaning job will often result in a satisfied customer. Always remove gum deposits with a good gum solvent. In many instances it may be advisable to install a fuel filter to minimize dirt deposits.

	18