Abstract: Apparatus for use in reconditioning engines by reworking or replacing the valve guides and seats thereof, which obviates any need for meticulously positioning a toolholder individually for each valve location. A toolholder bar has one end cross-bored to receive tool-guiding bushings, and the bar has a diametral slot extending axially along a major portion of its length, in alignment with the cross-bore. A pair of V-blocks with clamps is positioned on the head or block being reconditioned and the toolholder bar is positioned in the V-blocks, the arrangement being such that the axis of the bar is aligned with a row of valve locations. Alignment is facilitated by the use of a pair of aligning pins which pass through the slot in the bar after insertion in selected valve guides. When the V-blocks are now secured to the work piece, either of the aligning pins may be removed, and the bar may be slid axially until its crossbore is aligned with the first valve location, where it is clamped.