Abstract: A gaseous fuel-air mixture device for an internal combustion engine having an intake for a fuel-air mixture. A chamber for mixing gaseous fuel and air is provided above the intake. The gaseous fuel is uniformly injected into the mixture chamber from an aperture in the chamber wall. The quantity of air mixed with the gaseous fuel in the mixture chamber is controlled by adjusting the height of a control plate disposed above the chamber.

Abstract: An internal combustion engine dual fuel system for controllably running the internal combustion engine on a liquid fuel, such as gasoline, in the usual manner or, at will, on liquified petroleum (LP) gaseous fuel. The conventional liquid fuel system of the internal combustion engine is unmodified except for the addition of a remotely controlled shut-off valve in the fuel line at the carburetor fuel inlet. An LP gas suction verturi is disposed in the air induction flow to the carburetor inlet, for example by being mounted in the air filter above the carburetor inlet, and is supplied in fuel from the vapor phase of an LP gas, such as butane or propane, above the level of the liquified gas in an appropriate tank. The LP gas tank and the line supplying the gas to the carburetor air inlet are maintained at a substantially constant temperature via a by-pass of the engine coolant circuit, the flow of coolant through the by-pass being automatically controlled by a thermostat.