Flatten the cylinder head
The cylinder head may become warped due to overheating of the engine due to, for example, a leaky head gasket. Then it is necessary that the cylinder head is flattened.
To make a cylinder head suitable for LPG or unleaded petrol, the steel valve seats are replaced by seats made of stellite. They are harder and also dissipate the heat faster. In many cases, honing can replace internal grinding.
Extortion
The extortion is for looking up the barns in the cylinder head. This is always tested with hot water and put under pressure.
