I have never understood what Ford means in the manual when they describe how to adjust the centering spring on the power steering control valve. The 57 Manual says "tighten securely" and memory tells me that the description is similar in the 55 & 56 manuals. Does "tighten securely" mean to compress the spring fully to a point that you are getting firm resistance like an ordinary (without a spring) nut or does it mean to just make contact with the spring and then back it off a quarter turn? Without having it apart I can't remember if the rod is threaded far enough down to allow it to tighten all the way to fully compress the spring. A picture is attached below. Any thoughts would be appreciated.