Bill - the fuel level in the carburetor bowl depends on:
(1) fuel orifice in the fuel valve seat
(2) buoyancy of the float
(3) inlet fuel pressure
(4) the static setting of the float
The inlet pressure is stopped by the closing of the valve attached to the float IF the float buoyancy will overcome the inlet pressure on the load side of the seat. The seat orifice will effect the pressure on the load side; thus too large an orifice can cause the force on the load side of the seat to be greater than the force exerted by the buoyancy of the float, and the float cannot completely shut off the inlet fuel.
The correct orifice seats are readily available in the better carburetor rebuilding kits.
Actually, the 0.091 Walker valve is better than most of the cheap kits which use 0.101.
Jon.
