1992 Cougar ribbed belt install on 1992 Mercury Cougar

Attempting to install the ribbed belt. I have the alternator loosened up,but the belt is still 1/2 inch shart. WHat else do I need to loosen

Asked by for the 1992 Mercury Cougar
you may have the wrong belt. compare the numbers on the belts. they begin with k and see if they match