When Willys-Overland developed the flathead 6 around the end of World War II, management dictated that the cost of the project be as low as possible. To do that, the engineers tried to adapt everything it could off the 4 cylinder motor. Because of fuel volume requirements for the 2 extra cylinders & other considerations, a different carb was specified. If you try the 4 cylinder carb on the 6 cylinder engine, expect varying degrees of problems.
