To machine the rockers pedestals of my OEM 4 V Open chambers heads, I had indicated to the machinist that the axis of the studs had to be parallel to the axis of the valves and I had made a sketch BUT I had also provided this shema :
and he only looked at this one without taking into account what I had told him, but this diagram is FALSE because the original surfaces of the pedestals ARE NOT PERPENDICULAR to the axis of the valves and here is the result:
The correct geometry cannot be obtained, the rocker arm shaft is too close to the valve stem and the roller cannot press in the middle of the valve stem
I am currently studying a way to save these cylinder heads but I am not sure I can do it.
So do'nt follow the recommendations of this diagram!