to setup your rockers 100% correctly you will need to get a mag. base and dail, an adj. PR.
Bring the cam to its mid lift (I went from the PR as it has alittle hole in the tip to hold the dail needle). You go threw the cycle and find the low (no lift) and 0 out the dial.
take your cams lift and take out the rocker ratio (lift is cams lift * rocker ratio, if the cams numbers are for 1.6 / the lift by 1.6 to get the lift at the cam. bring the cam to 1/2 of its lift...ex. cam lift is .240 total...bring it to .120.
With the cam at its mid lift put alittle greese on the head of the vavle and place the adj. PR in place and install the rocker. Trq. down the rocker to the 25lbs. and adj. the PR so there is no lash. See were the rocker sits on the valve head. Your looking ot get it dead center.
You can also use a PR and run the rocker threw its cycle and with the greese on the valve head look at the length of the mark left in the greese. You are looking for the most centerd shortest travel of the rocker tip.
Shims will move the travel and "center" of the travel around on the valve head if your off.
Once you get the rockers propper travel setup then put the adj. PR in and trq. down the rocker. adj. the PR so there is no lash (up down movement/and slight drag)...measure the adj. PR. Remember you will need to add the pre-load lenght as well as you already trqd. down the rockers...so gen. you looking at adding alittle to get the amount of preload you want.