I have been a shade tree mechanic for over 50 years. In fact I have a 1950 GMC with no motor sitting under the same shade tree where I worked on GMC and Y-Blocks 50 years ago. About the time i got out of high school, and old shop closed up and I bought their Sioux valve machine with a rocker attachment as well as a stem truing and chamfering . So I was the first kid on the block to have uptown machine tools. I know lots have been done freehand, but I can't help but think that having the rocker tip parallel with the shaft has got to take stress off of the rocker bushings. Back when my father delivered gasoline with GMC, we might go through 3 or 4 new short blocks with the same rockers. That must have been around a half a million miles. We always had the rockers dressed at every valve job. However, none of our engines, except for maybe Cletis, gets driven that much any more.
