When a cylinder head is installed on the block, substantial valve seat distortion can be measured from the stresses induced upon the head, thus compromising cylinder sealing. Having the ability to grind or cut the valve seats in this distorted condition is advantageous.
The Cylinder Head or "H" Model precision Torque Plate is drilled and tapped to accept the installation of the cylinder head using the O.E.M. length cylinder head bolts or aftermarket studs and a gasket (bolt hole detail shown to left). With the head installed on the plate, valve seat distortion is duplicated during the machining process producing a substantially more efficient valve seal. Some cylinder heads show a 5-12% improvement in leakdown when valve seats are machined in this manner.
Some clearancing of the side wall of the plate may be necessary to fit large grinding stones or cutters into the combustion chamber on some applications.