In order to get your old belt off you'll have to loosen up the tensioner bolt and push the assembly back. Once you've got it back, tighten it up snug to hold it in place. When you get the new belt in place, loosen the tensioner bolt 180 degrees, rotate your crank counterclockwise 3 teeth and then re-tighten the tensioner. That sets the proper tension on the belt. I just finished doin the same job last weekend. It was a PITA but worth it for the money saved.