Abstract: A kit and method for converting a compression ignition diesel engine into a spark ignition natural gas engine is disclosed. The kit includes a throttle body, a fuel management system, a timing module, a means for reducing a compression ratio of a piston in the diesel engine, and a means for providing a spark in a cylinder of the natural gas engine. The method includes the steps of providing a diesel engine, machining one or more cylinder heads on the diesel engine to accept one or more spark plugs, machining a top surface of one or more pistons of the diesel engine to increase the volume of the one or more combustion chambers when the one or more pistons are located at top dead center in the diesel engine, providing a fuel management system to deliver the air/fuel mixture to the one or more combustion chambers, and providing a timing module to monitor the position of one or more camshafts on the diesel engine and provide piston position information to the fuel management system.