cylinder head four-valve mechanism Roof-shaped combustion chamber with four-valve mechanism. Distribution of the ducts for discharge and intake valves. By turning the camshaft the opening and closing of the valves can be demonstrated. description ordernumber 1230 see also: nozzle holder with hole-type nozzle Petrol direct injection engine M 270 Mercedes Benz injector for engines with direct petrol injection (GDI) engine of a VW Golf with transmission