Support for elastomeric disc valve in combustion driven fastener hand tool

A method of controlling combustion in a combustion driven hand tool having a control valve between two portions of a combustion chamber in a combustion driven hand tool including a flexible disc affixed to a movable central shaft, wherein the control valve is disposed in an open position with a circumferential edge of the flexible disc distal from a valve seat on a wall of the combustion chamber and control valve is disposed in a closed position with the circumferential edge of the flexible disc contacting the valve seat, the method comprising the steps of:

• affixing a plate to the movable central shaft adjacent the flexible disc and disposed on a same side of the flexible disc as the valve seat to support the flexible disc with the control valve in the closed position
• allowing combustion pressure to flow freely between the two portions of the combustion chamber with the control valve in the closed position under forward combustion pressure through one or more ports through the plate;
• and
• supporting the flexible disc with the plate such that the flexible disc does not collapse by the valve seat under reverse pressure.