Tool and method for the finishing of valve seats and guides

Tool for final machining of a valve seat and valve guide in the cylinder block of a combustion engine of a motor vehicle, said tool having a first section provided with at least one first blade for machining the valve seat and a second section provided with at least one second blade for machining the valve guide, a separation site provided between the first section and the second section, said separation site comprising a cone and a conical recess capable of receiving said cone the separation site including two plane surfaces of which the first one is disposed on the first section and the second one is disposed on the second section and wherein when the first and second sections are mounted together for final machining the first and second plane surfaces are firmly pressed together and the cone and conical recess are firmly pressed together thereby coaxially aligning the first and second sections.