Abstract: Apparatus for grinding a valve seat of an internal combustion engine using a conventional handheld power drill. A tubular housing provides a shoulder for aligning the tool with the valve and seat during operation. An inner member is concentrically disposed in the tubular housing and extends outwardly for attachment to the chuck of the handheld power drill to rotate the apparatus and attached valve during the grinding operations. A flexible portion of the inner member compensates for angular misalignment between the valve and seat in the handheld drill. A spring is concentrically mounted about the inner member between the tubular housing and an adjustable spring retainer for pulling the valve into contact with the seat with a preselected grinding force. Preferably, the valve is rotated in alternating directions during the grinding operation to insure proper seating.