The valve cone angle is the angle of the valve sealing surface, generally 45 °, and some are 30 ° (CA1091 car 6102 engine). The 30 ° valve is considered to have a small valve taper, a large valve passing through the end face, and a small inlet resistance when the lift is the same. However, due to the thin edge of the valve head with a small taper, small stiffness, and poor sealing and thermal conductivity, it is generally used for the inlet valve. The thickness of the valve edge is generally 1~3mm to prevent it from being damaged or burnt by high temperature due to impact with the valve seat during operation. In order to reduce the intake resistance and improve the intake efficiency of the cylinder, the intake valve of most engines is larger than the exhaust valve. The used inlet valves and exhaust valves also have different colors.

The valve stem is cylindrical and moves back and forth continuously in the valve guide. Its surface must be overheated and polished. The shape of the end of the valve stem depends on the fixing form of the valve spring. The common structure is that two half of the lock plates are used to fix the spring seat. The end of the valve stem has a ring groove to install the lock plate. Some are fixed with a lock pin, and its end has a hole for installing the lock pin. [1]