In a flathead motor, the valves are typically located in the engine block, rather than in the cylinder head like in most modern engines. The valve location can vary depending on the specific design of the engine, but in general, the valves are positioned on either side of the cylinder bore within the engine block.
They are operated by a camshaft, which is typically located in the center of the engine block and is driven by the crankshaft. The camshaft has lobes that push on the valve stems, opening and closing the valves at the appropriate times in the engine's combustion cycle.