To use, lightly machine (clean) the camplate relief valve seat and re-seat the plunger valveBest used in conjunction with Feuling pressure test tool part# 9010 or 9006, but can be used on OEM or aftermarket camplates.Feuling recommends installing a new relief plunger valve, see related parts.Used to perform a valve job on the pressure relief valve seat of any Twin Cam engine camplate and Milwaukee Eight oil pump psi relief valve bore.