The float system controls the level of gasoline in the carburetor and admits fuel as necessary to maintain the proper fuel level throughout the operating range of the engine. As the fuel level lowers, the float lowers and the float valve (3) opens to admit more fuel to the float bowl. As the fuel reaches the operating level, the float rises, closing the float valve, which shuts off the fuel supply. Actually, during normal operation the float assembly positions so that the inward flow and the outward flow are about even. The float system is a dueal float mechanism, used in a float chamber or fuel bowl that almost completely surrounds the main discharge nozzle. This construction permits operation of the enging at any angle up to 45*.

The float is typically made of brass and sits on top of the fuel in the float chamber. It is connected to a hinge or pivot using a float pin.

ADJUSTMENTS & SERVICING

• Examine the float and needle & seat valve for any signs of wear.
• Test brass floats by submerging them in hot water. If you see any bubbles, your float has a pin hole and needs to be replaced.
• Always replace nitrophyl (plastic) floats during a rebuild. They will absorb fuel overtime and as they are not hollow, water testing them won’t work.
• Set the float according to the image. Be careful not to push down on the inlet needle while making adjustments.

REPLACEMENT FLOATS

There are three primary floats used in the Marvel Schebler carburetors. They can sometimes be identified by the TSX-??? ID number used on all Marvel Schebler carbs. In some cases, the float needs to be matched by comparing dimensions of the carb.

When referencing the bowl size, measure across the longest point of the bowl gasket

“Small bowl floats” are used in MS carbs with a 4” bowl length.

“Medium bowl floats” are used in MS carbs with a 4 3/4” bowl length.

“Large bowl floats” are used in MS carbs with a 5 3/16” bowl gasket