I don't believe that there is any magic to it. I changed the pin on the SD to improve the idle quality and the new pin has more spring tension in it. I simply screwed it in until it makes contact with the rack and then turned it in another two turns or so to preload the spring. You don't want to use more tension than you need to get a smooth idle. If you are quite ambitious, simply screw it in one turn past initial contact and try it. If the idle is not satisfactory, try one additional turn and evaluate.