Starting a Gas/Diesel engine.

We will start a 1940's International UD18 gas/Diesel engine. I installed this engine on a lane sawmill and have been using the Gas Diesel on the mill for about 20 years. I will explain about the operation and how this engine transfers from a Gasoline motor to A diesel engine with the pull of a lever. I would like to say if you have one of these and are having trouble starting it look for two things. First and most likely problem will be weak spark. Some of theses engines had distributors if yours has a distributor you will need two good 12 volt batteries wired in parallel. It takes a lot of power to turn this motor. If you do not have enough battery power it will cause weak spark. Make sure the points are perfectly clean and adjusted. Pull the coil wire and you should get a spark that is a nice blue and will jump at least 3/8 of an inch. If you have a magneto the impulse cuppler must be free and working. Pull a plug wire and while turning the engine you must get at least a 1/4 inch blue spark to ground. If not check the points if they look good the magnet may need to be recharged. Mainly Magnetos can rebuild it and recharge the magnet. You can do what I did and make the magneto into a distributor.
The second problem could be the valves that open into the antechamber for the decompression and spark plugs. If the engine has set they could be stuck or the air intake to the carburetor could be stuck or the carburetor. There is a linkage that hold the gas float from letting gas in during diesel run. There is also a switch on the manifold linkage that turns off the spark, I have since sold the mill but I have a gas diesel engine and a hood for a UD18 if there is a need.