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Most V8s have a heat riser passage that runs from an exhaust port on each side to heat the intake manifold. It is done to aid warming up the engine quicker but has the added benefit of warming up the carburetor also,lessening the chance of ice. Most cars have downdraft carbs which are less prone to carb ice than updrafts that are used on aircraft. I don't know why they are less prone other than above. Some stationary power plants like welders and such use updraft carburetors and do get carb ice. I have seen heat muffs fashioned to essentially provide carb heat. I'm only guessing but I would suspect one large venturi(such as aircraft carb) would do more cooling in a localized area than 2 smaller ones spread apart like most automotive. Also most watercooled cars have hot water circulating through intake manifold keeping carb warmer than one carb hanging down in the air in an airplane. The other factor I could think of is aircraft are run at virtually wide open throttle creating a lot of air over venturi,thus more cooling. Cars run at very closed throttle settings mostly and would not have nearly as much cooling going on in the venuri relative to full throttle. And if a car dies and coasts to side of road, with a 190 degree motor, the ice would probably melt by the time the driver restarts it, probably receiving no further investigation.
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