Valve springs should be inspected before installing them on the cylinder head. In fact, all valve train components and their geometry should be checked before reassembling the valve train. Valve springs are made from different metals depending on the engine. There are several designs other than standard springs. Some include a damper to reduce valve train vibration. Others are variable springs that change the distance in the space between the coils. Dual springs have a smaller spring located inside the larger one. This spring set dampens and reduces vibrations.