Why does the manifold frost up?

Hey Meli...
    : Does anyone know what would cause the intake manifold to frost up when running?

Pay Attention!!!
Hi ya,
    Any time a liquid evaporates quickly, it absorbs heat from its surroundings. That's why alcohol feels cool on your skin. That's the principle behind refrigeration. Take a look at the illustration below and see what goes on inside of a carburetor. As the gasoline vaporizes in the throat of the carburetor, it absorbs heat from the entire body of the carb and the intake portion of the manifold and makes it COLDER than the ambient temperature of the surrounding air.

The gasoline vaporizes in the venturi of the carburetor
Pay Attention!!!

    At THIS particular time of the year, when the temperature is near, or BELOW freezing, ANY moisture that is in the air will FREEZE on the carburetor and manifold. This icing doesn't cause any harm... UNLESS... unless there is moisture in your gasoline. Then IT will freeze, too, and clog up the passages in the carburetor. If you use your tractor in the winter, it's a good idea to put alcohol-type "dry gas" in the gasoline. This is even MORE necessary than using gas-line antifreeze in your car because the gas in your tractor usually sits in a half empty tank a lot longer and is more likely to absorb moisture.

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