I have an old air hose set up that uses one the cylinders from a gasser engine as the compressor. You unscrew one of the spark plugs and screw in the adapter into the spark plug hole, hook up the hose and you have a hose to put air in your tires or hook up a pressure tank to collect the compressed air and use your engine as a cheap air compressor. The air line even has an in-line air pressure gauge. Works great but don't smoke around this contraption as there is gasoline in the air mixture.
