Fuel injectors, for hydraulically actuated fuel systems with complex seals so high pressure oil can be confined, are assembled in an engine head with a tool that fits with part of the injector. The shield fence includes a porous sidewall through which molding compound passes during molding of the shielded package. The rotary elements of two or more valves can constitute disc-shaped sections of a single rotor confined in a valve body common to all valves.