Abstract: Marine drives having water cooled engines utilize a water pump mounted over the drive shaft and internal to the drive shaft housing to provide engine cooling, the pump having stamped metal housing parts and a flexible impeller.

Abstract: A marine propulsion apparatus includes an external combustion engine having a fuel pump connected by an electrically operated anti-syphon valve unit to a storage tank. The electrically operated anti-syphon valve unit includes a resiliently loaded valve means which is moved to open the valve unit either by an electrical operating means or by the normal pressure differential created by operation of the engine fuel pump.

Abstract: A vapor sensitive resistor, or switch, is connected in a bridge network having the input connected to the battery of a marine engine. A window signal comparator includes a high limit operational amplifier and a low limit operational amplifier, each have a first input connected to the opposite sides of a reference resistor in the bridge network to establish relatively high and low reference voltages and second inputs connected in common to the sensing resistor. The amplifiers include a positive feedback and two outputs are connected to an "OR" logic gate which is connected to drive a two-stage transistor amplifier wholly on or off. An alarm device is connected in series with the amplifier to the battery. A test switch varies the circuit connection of the vapor sensitive resistor to simulate a high or low limit condition and thereby test circuit operation.

Abstract: A solid state ignition system is provided for a two cycle internal combustion engine. A low speed limiter unit includes an electronic spark advance controller means connected to the ignition system to automatically advance the ignition angle by a substantial amount below a desired low limit speed. A speed sensing means is connected to sense the engine speed and at the selected minimum engine speed actuates the advance controller. The advance controller preferably has an asymmetrical rate of response, producing a relatively rapid advance output and a relatively slow retard output in response to changes in the speed sensing means.

Abstract: A heat exchanger is provided for a pressurized, closed cooling system for a marine propulsion engine. The heat exchanger includes a closed spiral passageway means for the fresh cooling water drawn from the lake or other water body. An outer housing encloses the spiral passageway and includes baffle means for directing of a coolant in a spiral path over the cooling passageway means within the housing. The coolant is thereby cooled by the circulating cold fresh water. An air discharge passageway means is provided in the center of the spiral path. The centrifugal forces associated with the spiral flow of the cooling coolant results in the water moving outwardly within the passageway while the air tends to collect within the center thereof where it is collected and discharged by the air passageway means for automatic separation and removal of the air.