Carburetor icing

From Glossary of Meteorology

carburetor icing

The formation of ice in the throat of a carburetor as the result of cooling by expansion and evaporation of gasoline.

At one time a serious problem in aviation, carburetor heaters now render this unimportant. Carburetor icing often occurs at ambient air temperatures as high as 50°–60°F, the necessary cooling to the frost point occurring within the carburetor throat.
Compare aircraft icing.