Lots of bad info in this post. I paid 400.00 for my valve grinder and cleaned it up years ago. I have and can do valve seats with stones but I rarely do it anymore. I bought used Neway valve seat cutters off Ebay and pilots for every application I need them for. When I go to a bigger valve size I could do it but it’s very time consuming so I have them stripped down and cleaned and a local shop charges me 80.00 to open up eight intakes and do the valve job needed for the bigger valves.