A slidable mobile terminal including a first body having a first surface and a second surface, a second body having a first surface and a second surface, the first body being movable with respect to the second body between a closed position where the first body substantially overlaps the second body and an open position where the first body partially overlaps the second body, is provided. The valve assembly includes a port in a firing chamber in an engine head, the port having a valve seat on a side opposite from the firing chamber. Other embodiments are described and claimed.