The pilot was on a local flight when the engine failed suddenly at about 1500 feet above ground level. Emergency checks failed to restore power and the pilot made a forced landing approach to a paddock. During the approach he deployed the drag brake because he was slightly high. He then saw a power line he had not previously sighted. In clearing this line the speed washed off and the aircraft touched down heavily, fracturing the main gear legs as a result. An examination of the aircraft revealed that the fuel gascolator drain valve had been lost in flight. This resulted in fuel draining from the fuel bowl which in turn resulted in the engine power loss. The reason for the valve separating is not known. The information in this report is based on details provided by the pilot.