Cylinder head definition
The detachable metal (aluminum or iron) section that is bolted to the top of the cylinder block . It is used to cover the tops of the cylinders, in many cases the cylinder head contains the valves, it also forms part of the combustion chamber . It has water and oil passages for cooling and lubrication. It also holds the spark plugs . On most engines a valve cover or rocker arm cover is located on top of the cylinder head. Some engines have just one cylinder head covering several cylinders, while others have separate heads for each cylinder. In some motorcycle engines and small engines, the cylinder head is not detachable -- it is cast with the cylinder which forms a blind hole.