Chrysler Air-Raid Siren Maintenance Manual

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The carburetor is of the down-draft type and is equipped with fixed jets which cover all speed ranges except the idle range, which is controlled by two adjusting needles. The carburetor is equipped with adjustable accelerating pump and a fast idle device for the prevention of stalling while operating below normal temperature.

The idle needle valve controls a fuel mixture for closed throttle operation. Turning the adjustment screw clockwise gives a leaner mixture and counter clockwise a richer mixture. (A vacuum gauge is desirable when adjusting idle needle valves to obtain the highest reading.)

The carburetor float level may be checked by removing the inspection screw plug in the side of the body. The fuel level should be even with the bottom of inspection hole with the engine idling. Two positions are provided on the accelerator pump lever in order to give a greater or lesser discharge of fuel, depending upon climatic conditions.

For warm weather or for high altitudes above 3,000 feet the pump link should be in the hole in the accelerating pump lever which is nearest to the throttle shaft. For cold weather operation, the pump link should be in the pump lever hole which is farthest from the shaft.


The heavy duty oil bath air cleaner mounted on the carburetor is a protection against dirt, dust and abrasives entering the engine through the carburetor. The air cleaner should be cleaned and re-oiled at least twice a year.


An automatic choke controls the mixture of gasoline and air at the carburetor according to the temperature of the engine, and operates when starting and during the time the engine is reaching operating temperature. After the engine is warm (due to the heat of the exhaust manifold affecting the choke) the choke valve opens and stays in this open, or "off" position until the manifold cools.

The automatic choke and its linkage, both at the choke and the valve in carburetor air horn, should under NO CIRCUMSTANCES BE OILED OR LUBRICATED. All of the moving parts should be dry and free. Oil will cause sticking and unsatisfactory engine performance. Dirt, oil or anything that retards the free action of the linkage (particularly the choke valve pivot pins in the carburetor air horn) should be washed off with a gum solvent. This is particularly important during cold weather.


  1. Open throttle one-fourth way.

  2. Remove air cleaner from carburetor and cover from automatic choke.

  3. Line up the hole in the armature and the hole in the magnet core, and clamp in this position.

  4. Loosen clamp screw on automatic choke lever and move the lever down until carburetor choke valve is tight. There should be no play in the choke valve.

  5. Hold lever in this position, tighten clamp screw and replace automatic choke cover.


The gasoline gauge is of the plain float type, protected by a wire screen located in the top center of the gasoline tank protruding through the engine hood. The capacity of the gasoline tank is 18 gallons.

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