A valve operating system for engines of the type including a main combustion chamber having intake and exhaust valves, an auxiliary combustion chamber having an auxiliary intake valve, a spark plug, and a torch nozzle communicating with the main combustion chamber; the valve operating system including main and auxiliary rocker arms for actuating the main and auxiliary intake valves which are operated by a common upper tappet, a push rod and a lower tappet connected by ball and socket joints, the lower tappet being cam operated. A similar cam operated assembly, including a rocker arm, is provided to operate the exhaust valve.