Abstract: A stern drive marine propulsion system (2) has an inboard engine (4) with an exhaust (6), an outboard drive unit (8) and propeller (14) operatively coupled to the engine and separated therefrom by a transom (10) having two exhaust passages (28 and 34) therethrough, and an exhaust control assembly (16) having an inlet (18) connected to the engine exhaust, first and second outlets (22 and 24) communicating with respective exhaust passages extending aft through the transom, and a valve (26) in the assembly having a first condition (26a) providing communication of the inlet with the first outlet, and a second condition (26b) blocking communication of the inlet with the first outlet. Automatic control circuitry automatically controls actuation of the valve between the first and second conditions in response to a given parameter.

Abstract: A combination exhaust manifold and exhaust elbow for an internal combustion engine includes an exhaust cavity for receiving exhaust from the engine, an exhaust passage leading from the exhaust cavity, and an exhaust discharge outlet. A first water jacket is provided around the exhaust cavity and a second water jacket is provided around the exhaust discharge passage. A dam is provided between the first and second water jackets, having a passage therein for allowing fluid communication between the first and second water jackets. A warm water inlet is provided in the first water jacket around the exhaust cavity for receiving cooling water which has been warmed by the engine, and which flow is controlled by a temperature sensitive thermostat. A cold water inlet is provided adjacent the discharge exhaust passage.

Abstract: An evaporable foam pattern for casting a metal water-cooled exhaust manifold for an internal combustion engine. The assembled pattern is formed of an evaporable foam polymeric material, such as polystyrene, and includes an inner exhaust conduit composed of a generally upright body portion and a generally curved elbow portion. The body portion is provided with a plurality of inlet ports connected to the exhaust passages of a bank of cylinders, while the elbow portion defines a downwardly facing outlet. The pattern also includes an outer water jacket which is spaced from the exhaust conduit to provide a water passage therebetween. Both the exhaust conduit and the outer jacket are composed of two longitudinally split halves or sections having abutting edges, and the abutting edges are joined together by an adhesive. Spacing ribs interconnect the inner surface of the jacket and the outer surface of the exhaust conduit to space the sections apart.