Upper Casting Passages

• Casting Passages for the flow of gasoline and air are critical "Components" of the carburetor that are often overlooked. Sections of some passages had to be drilled via the outside surface of the casting. Then the ends were filled with brass plugs. When rebuilding carburetors, I recommend that the plugs be drilled out, passage cleaned out, and then re-plugged. These Brass plugs are available at most Model A parts suppliers.
• The Green line identifies the large passage for gasoline to get to the Float Bowl from the Fuel Input Line, via a Passage through the Strainer and Float Valve. In addition to this passage clogging and fuel lines clogging, Strainers do deteriorate, with particles getting into Jets, etc.
• There's a small Idle Port in the throat, just above the closed, Throttle plate. The Red line notes that there's a gasoline Passage from the idle jet opening to the Idle Port in the Throat. This port provides gasoline and air at idle conditions via passages.
• The Orange line identifies air Passage from just to the rear of the Idle Jet opening that goes to the Idle Port, via the Air Adjust Screw.
• It was found that the Float Bowl needs to be vented to atmosphere to prevent conditions that could affect Float Valve operation. There's a small Air Vent Passage between the area above the Float Bowl area and the area just above the Secondary Well.

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