Here are the instructions for the rocker attachment for my 70 year old Sioux valve machine. I haven't worked a head in a long time. But I am hoping to get back to doing a little of it since I auctioned off my trucking business and have the shop to myself now. Years ago I used it a lot because I saw a lot of rockers with a pretty deep grove knocked into them making it impossible to adjust the valves properly. It wouldn't surprise me if the engine manufacturers didn't use something similar when they built the engines. 75 years ago.
