Complex sentence: The spark plug and CVCC inlet was isolated from the main cylinder by a perforated metal plate; upon ignition flame fronts shot into the very lean main charge through these perforations, ensuring complete ignition.
Split into simpler sentences: The spark plug and CVCC inlet was isolated from the main cylinder by a perforated metal plate. At ignition a series of flame fronts shot into the very lean main charge, through the perforations, ensuring complete ignition.