Float Valve and Float

• Gummy residue from old gas in the bottom of a tank will cause continuing float valve problems, until tank is cleaned out.
• Float Valves must be very tight against their gasket or they leak, especially if casting threads are sloppy.
• When installing a valve, I recommend pushing the Valve Stem in hard and twisting a few times to seat it.
• The desired fuel level in the main well is 9/16 to 5/8 inches from the gasket surface of the bottom casting, with the engine not running.
• If the fuel level is set to 1/2" (from the gasket surface of the bottom casting, with the engine not running) it can allow some carburetors to stall when the vehicle comes to a quick stop. If the fuel level is less than 1/2" (from the gasket surface of the bottom casting, with the engine not running) it can allow some carburetors to drip gasoline from the air intake. If the fuel level is set greater than 11/16" (from the gasket surface of the bottom casting, with the engine not running) it can allow some carburetors to run lean mixture, with rapid acceleration.
• I prefer to use white neoprene gasket washers, which are .043 to .046 inches thick, under the float valves. The desired number to use under the float valve to obtain 9/16 to 5/8 inches of fuel in the main well varies with the valve design used.
• PN A9564-A Original type valve needs 1-2 washers.
• PN A9564-M Modern design valve with Neoprene seat needs 3 washers.
• PN A9564-Z Stainless steel ball, with O-ring seat needs 2 washers
• Sometimes, one needs to sand down a gasket washer thickness to get the float level set correctly. Measure the bowl fuel level using an external tube gauge. Most Model A parts suppliers carry them.
• The Float Valve threads are 1/2" 20 UNF (SAE)
• Inspect Float for a small dimple worn into the top of the float from valve needle rubbing. The effect of this dimple is a lateral bind on the valve needle that prevents it from closing completely and sealing.
• Floats can leak gasoline into them, and don't float very well.
• To pressure test Float for leaks, see Float Tester.

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