Dual fuel system

A dual fuel system for an automobile engine having an intake manifold forming an intake opening, and an exhaust manifold comprising:

• at least two fuel tanks;
• at least two carburetors, each communicating with a fuel tank and having a common throttle linkage and an outlet port;
• and
• an adapter assembly forming a pathway between each outlet port of a carburetor and the intake opening, the adapter assembly having
• a venturi means forming at least two venturi throats, each throat in registry with an outlet port of a carburetor, and forming a helical duct which spirals about a selected venturi throat and communicates with the exhaust manifold so that heated exhaust gas passes about the selected venturi throat and preheats an air-fuel mixture passing therethrough;
• and
• a valve means including two butterfly valves, each positioned within a venturi throat of the venturi housing, a valve linkage which remotely controls the position of the butterfly valves such that as a first butterfly valve is in a closed position thereby closing the pathway from the respective venturi throat to the intake manifold, the other butterfly valve is in an open position thereby opening a pathway from a venturi throat to the intake manifold;
• and a slave linkage which is connected to a distributor on the automobile engine so that the timing of the distributor may be changed when a predetermined pathway is opened by the valve.

In an automobile engine having an intake manifold forming an intake opening;

• an exhaust manifold;
• and two carburetors, each supplied by a separate fuel source;
• an adapter assembly forming a pathway between an outlet port of each carburetor and the intake opening;
• the adapter assembly comprising:
• a venturi means forming at least two venturi throats, each throat in registry with an outlet port of a carburetor;
• an adapter means forming a single passage therethrough and including an end adapted to be mounted on the intake manifold such that the passage is in registry with the intake opening;
• and
• a valve means, located between the venturi housing and the adapter means for alternately opening and closing a pathway from a preselected outlet port to the intake opening so that only one outlet port communicates with the single passage at a time.

In an automobile engine having an intake manifold forming an intake opening;

• an exhaust manifold;
• and two carburetors, each supplied by a separate fuel source;
• an adapter assembly forming a pathway between each outlet port of a carburetor and the intake opening, the adapter assembly comprising:
• a venturi means forming at least two venturi throats, each throat in registry with an outlet port of a carburetor, and forming a helical duct which spirals about a selected venturi throat and communicates with the exhaust manifold so that heated exhaust gas passes about the selected venturi throat and preheats an air-fuel mixture passing therethrough;
• an adapter means forming a single passage therethrough and including an end adapted to be mounted on the intake manifold such that the passage is in registry with the intake opening;
• and
• a valve means including two butterfly valves, each positioned within a venturi throat of the venturi means, a valve linkage which remotely controls the position of the butterfly valves such that as a first butterfly valve is in the closed position thereby closing the pathway from the respective venturi throat to the intake manifold the other butterfly valve is in an open position thereby opening a pathway from a venturi throat to the intake manifold, and a slave linkage which is connected to a distributor on the automobile engine so that the timing of the distributor may be changed when a predetermined pathway is opened by the valve.