For those that have this valve this question is for you.
I am using a standard GM type power steering pump and a mustang power rack.
I have mine so that there is 4 full turns from where the adjustment knob has no more threads and comes off the body. Not sure how few threads is safe to have with the pressure in there. If I turn it all the way in I count about 8 turns of adjustment. As I remember from the instructions turning it counter clockwise was supposed to make the power steering effect less.
I don't know if it is safe tur turn it our more turns or not. But it is still kinda sensitive.