Don't spin the valve with a drill or anything like that. Flip the head upside down with the valves removed from the head. Put a little lapping compound on the valve seat,slide the valve into place (careful not to get compound in the guide) There is a tool that looks like a stick with a suction cup on the end. Put the suction cup on the valve head and move back and forth between your hands. Take the valve out now and then to look and see if the whole valve seating area has been done. It should be a uniform greyish color all the way around on valve and seat.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!