John,
The Schrader valve that you are referring to has little or no use in the application that it is used in on a Beaver. In an application were a transfer pump is used before the Racor filter housing (Beaver does not use one), the Schrader valve can be used to check pressure or bleed air. However, on a Beaver the only possible use for the valve is to bleed air, but this will only work if you have a full fuel tank because you will be using gravity instead of pressure to purge the air.
Gerald