The stoppers determine the range of advance from initial to full, start with the blue stopper. That will allow for 21 degrees of advance or 14 initial and 35 full advance. If you want all your timing in at 2500RPM use the light blue spring and the light silver spring. Adjust accordingly. This can all be calculated from the tables in the instructions, if you don't have them you can get them on the MSD or Summit sites

Ken