the springs change the speed that the advance comes in , heavier springs take more RPM to allow the advance , conversely lighter spring bring the advance in sooner .
Newer dist built in the last 4-5 years have 2 torx set screws that can be loosened to alow a limiter plate to be adjusted for more or less curve . The older Dist have to be disassembled & the slots welded to shorten the travel .