Rev - Nov 26, 2017
By Jan Zumwalt (EAA #66327)
For additional information on this topic see VW Type 1 & 2 Carb Heat.
Some VW 1/2 conversions do not include carb heat; excluding it is very risky business. If a builder does not want to include a carburetor air box, it would be wiser to mount the carb close enough to the case or head so that it is kept warm enough to prevent ice formation. Shown in the pictures below are some options to consider.
The two designs shown above may be prone to carburetor icing. It is possible the heat coming off the head is
warm enough to prevent ice most of the time. But an extended descent at idle may cause serious problems.
(The author has had this occur and knows of cases where the pilot was forced to use full throttle.)
The first three (3) designs place the carburetor intake directly behind the hot oil
sump and give the carb a constant supply of warm air. The last design places the
carb directly on top the warm engine case, keeping the carb body permanently warm.