On the older BXs the 3ph vaqlve works similar to the way your fel valve does. pull back and it goes up let go and it stops. I am not all that clear on how a1/4 inch valve works but it is still not position control where you move the lever a little bit and the 3ph moves a little bit. In other words it moves in direct relation to the position of the lever. Move the lever three quarters of the way up and the 3ph will move to that position, three quarters of the way up.