The camshaft in the cylinder head is responsible for opening and closing the valves at the proper time. In the case of a 1, 2 or V engine, we can talk about 4 camshaft engines, depending on how many valves per cylinder the given cylinder head has. If we are talking about a 2-valve engine per cylinder, then the intake and exhaust valves are operated by the same camshaft. If we are talking about 3, 4, or even 5 valves per cylinder, there are 2 camshafts in most cases. There is a solution where 1 camshaft is provided with 16 cams and actuates the valve 16 by means of individual pendulums. Eg Suzuki G16B engine. There are only shafts that move the intake and exhaust valves, and in the case of cross-valved cylinder heads, the cams that move the intake and exhaust valves are replaced on the camshaft. It can be made of: solid, cast, forged or expanded tubular shafts.