This precision alignment tool is designed to locate the cam gear on any single cam Big Twin model 1970-1999 and duplicate the exact position when installing that gear on another cam shaft. This allows you to preserve the cam gear to pinion gear fit when installing a different cam. Not only can you install the gear in the exact same position, this tool allows you to advance or retard the gears position by up to 10 degrees with an accuracy of 1/4 of a degree. You can now turn a difficult and time consuming job into a simple and accurate job. A shop press will be required for the gear removal and installation. Complete instructions are included.