Joined: Jun 2009
Location: South San Diego
If the belt is loose and you can't tighten it any further, you need a shorter belt. That being said, it is always a good idea to get the right parts. I wouldn't try to add a tensioner; it never had one to begin with, so trying to add one will only complicate things and be more jimmy rigging.
'65 Coupe, 302, Autolite 4100, C4, 3.00