The valve guides centre the valves in respect to the valve seats and compensate for the lateral forces acting on the valve shafts. In addition, they need to dissipate the generated heat towards the cylinder head. Depending on engine design, identical or different valve guides are used for the intake and exhaust side. The range of materials reaches from gray cast iron and brass to sintered materials of various alloys.

The valve seat insert has the task of sealing the combustion chamber against pressure loss. In addition it is responsible for heat dissipation. Another important task is to prevent impacting of the valve into the softer cylinder head material. Valve seat inserts are predominately made from chromium-steel alloys. Also sinter materials are now increasingly being used.