Abstract: A liquid cooled exhaust manifold with spaced and separated passages associated with each exhaust port of an associated internal combustion engine and with a transversely extending common coolant distributing passage to evenly supply the separated coolant passages.

Abstract: Vacuum, created by venturi effect of the throttle valve within the throat of a carburetor of a two cycle outboard motor, in company with a vacuum source orifice positioned opposite a peripheral edge of the throttle valve, is partially applied, by strategic placement of a vacuum source hole, to the fuel float chamber of the carburetor to reduce fuel flow over a selected range of engine RPM; normally when the boat it is driving is cruising on plane. A changeable vent to atmosphere is used to adjust the vacuum level to compensate for altitude changes and to adjust the carburetor to a particular motor. An expansion chamber in the vacuum source line may be required to prevent engine hesitation upon acceleration.