After fighting the altenator on my son's Euro car,(1985) I found that two open end wrenches worked best. Once the upper and lower bolts are loosened, you can access the "tube nut" and run it down towards the altenator. This action causes the altenator to tighten as the tube nut runs on a bit of threaded rod, which is welded to the front side of the upper nut. You should have no more than 1/2" deflection in the longest side of the belt when tightened.