Hydrogen gas electrolysis and supply apparatus and method

A method of tuning an internal combustion engine to run using hydrogen gas as a fuel source is disclosed. The engine is one that has been designed to run on hydrocarbon fuels and has had no previous modification to operate on hydrogen fuel. The method involves modifying the timing of the intake valves of the engine to close earlier prior to combustion and/or open later after combustion, so that the duration of intake valve opening is reduced. The engine may then be run on hydrogen gas, which has a much faster flame speed in comparison to hydrocarbon fuels. The intake valve timing adjustment removes the possibility of a hydrogen ignition flame travelling back up through the intake valve.