I cant get more than about 2-300 miles on a belt with an Alta 19% pulley.I will say that i do run the car hard sometimes,but not all the time.I just replaced the belt tensioner and idler assembly along with the crankshaft pulley.I know these are installed properly,I triple checked everything.I did notice something and i am not sure if this will make any huge difference.While the engine is at idle, the belt rides on only about 2/3rds of the idler pulley.Also the alternator looks to be slightly out of alignment with the other pulleys.Could it have shifted?I have had problems with other bolts coming loose.Is there any adjustment on the alternator???Could these factors be affecting my belt life??I am about ready to push this car off a cliff.
The only way i feel safe in this car is keeping a set of rhino ramps, a tool box,
and a case of belts in the back.

 

Sounds like an alignment issue. Are you using the Alta crank pulley? Does one edge of the belt wear more than the other?

Edit: Just noticed you said: "While the engine is at idle, the belt rides on only about 2/3rds of the idler pulley" Do you mean the belt is hanging off the idler? That isn't right at all!

 

Get a Bentley manual, tear it all apart and try again, something's obviously wrong with your setup.

 

Because of the slight twist misalignment of the alternator, i guess its causing the belt not to ride fully on the idler.Can the alternator be adjusted? It's virtually impossible to see without removing the front end of the car.

 

Describe what you mean by " its causing the belt not to ride fully on the idler"

Is the belt hanging off the edge of the idler or is it over the idler, but simply at a different angle?

 

The belt is hanging off the idler

 

I looked again at the alignment of the pulleys and idler.All of the pulleys are perfectly aligned with the exception of the alternator.I guess that must be the problem.

 

Maybe your alternator got whacked when you broke the tensioner? As Ryephile suggested, get a Bentley manual and get everything in spec.