Funny you mention this. Maybe it's different on the 40v V8s, do you have a pic of the tensioner on that? On the ABZ the tensioner pulley is on a sprung bracket that keeps tension on the belt. An ~8" shock absorber/damper looking thing bolts to the timing cover and to the tensioner pulley bracket. I ran the motor without the damper and I saw the tensioner moving and the belt tracked off. I then had my buddy hold a 13mm wrench on the tensioner to keep it tight and it seemed ok. The part from the dealer is over 200 bucks so I made a solid rigid bracket to hold things tight. Only downside to my design is that over time as the belt stretches I won't have the damper to auto tension the belt. I'd have to check it, and keep retightening it as it loosened up.