For most repairmen, the machining of cylinder head seats is an even more mysterious process than, for example, honing. It is in the machining of seats that 100-year-old myths still prevail among engine mechanics, not only preventing the correct repair of seats, but even simply understanding the essence of this type of machining. Meanwhile, being a captive of old-fashioned techniques, not knowing either the technologies or the equipment for machining, it will not be possible to repair the cylinder head of a modern engine. Just as it will not be possible not to get into a mess, not to fall into a puddle, not to get caught on a rusty lure or a beautiful wrapper, but to make the right choice from dozens of possible options when it is necessary …