What material are carburetors made of?

Answer 1

There are three main materials of which carburetors are made: cast iron, zinc and aluminum. Starting in the 30's, cast iron started to be replaced by zinc and in the late 50's, aluminum replaced a lot (but not all) zinc.

In most cases, cast iron is finished in black oxidethough it's sometimes painted black. Carter recommended a special black carburetor paint when rebuilding a carb. Thus, while carbs like the W-1 Carter were originally black oxide finished cast iron, many of them are now - correctly - a semi-gloss black.

Rochester carbs also used cast iron in the throttle body section. This part was always black oxide and there was no factory paint recommendation.

The most well-known carburetor material is olive-green colored zinc. Zinc itself is a bright silvery metal that reacts with air and water to make a powdery white material often called 'white rust' . To prevent this, carburetor parts are treated in the factory with a chromic acid solution, which forms a thin layer of 'zinc chromate' on the surface of the metal. This very effectively protects the metal underneath from being damaged by water or air. This is why carburetors are usually green!