The cylinder head links the combustion chamber with the intake and exhaust system; it can be made of aluminium or cast iron.

The cylinder head is places on the crankcase e between them a gasket is places, called cylinder head gasket. Everything is tightened with cylinder head bolts. The force with which screws are tightened is called ‘tightening torque’.

The cylinder heads in the catalogue can be:

• BAre: have only the guides (hollow cylinders in which the intake and exhaust valves slide);
• Complete: they have the guides, springs and valves (and, where applicable, valve oil seals). They can also be complete with camshaft;

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The intake and exhaust valves are driven by one or two camshafts, depending on the engine. The valves act as ‘plugs’ allowing or obstructing the inlet flow of air or mixture (depending on the type of injection) and the outlet flow of exhaust gases. The camshaft is connected to the crankshaft via a timing system that can be driven by a belt, chain or cascade of gears.

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The cylinder heads house the injectors in housings that can have a flat or conical bottom, this characteristic determines which cylinder head to offer and which injector will be assembled on the cylinder head. The injectors are the organs through which the fuel, pressurised by the injection pump, is atomised in the cylinders.