The Marvel-Schebler TSX is a cast-iron updraft carburetor produced from 1939 to about 1979. The first applications were the TSX11 used on the Case model D and the TSX13 used on John Deere model L tractors starting with S/N 625000, both in 1939.
There are three basic sizes of TSX, small, medium and large. These each use their own bowl gasket and float. They can be distinguised by measuring the screw spacing in the float bowl, as described in our article on identifying TSX carburetors from measurements. Within each basic size, the airflow capacity is fine tuned by using different venturi inserts. Calibration is controlled with many different jet sizes and a variety of nozzles. Most calibration parts are available and can be looked up by referring to the TSX numerical list. The most common TSX parts are listed in our TSX parts visual guide.
TSX carburetors can be a fixed main jet design (Type A) which has no adjustment for the main jet, or can have a main jet that is adjustable from the outside of the carburetor. The adjustable carbs can be Type B, which has an adjusting screw in the throttle body (top part of the carb), or Type C, where there is an adjuster in the underside of the float bowl.
Some TSX carburetors have a fuel shut off solenoid in place of the main jet adjustment. These stop the fuel supply when the ignition is off and usually also adjust the main jet flow.
All TSX carburetors have an idle adjustment screw in the throttle body, near the top of the carb.