throwing belt..., alternator belt keeps flying off?? Options

[crash914]

anyone have this problem?

It all started when I replaced my gas tank.. before that I never had a problem.

Now I have thrown the belt 3 times in 3 days....

I did advance my timing a little bit. Could I be revving too fast?

this is not a stock motor... I just don't know if there are shims or other things to look at. Fan is tight and balanced..

I guess I could back off the timing, but what fun would that be...

[draperjojo]

I think Bartlett nailed it. Generally when you start throwing belts you need to look at belt tension, belt condition, alignment, and condition of pulleys. In this case you would probably need to check alternator bearings also, and it sounds like you've done that. After a number of years, the belt profile in the pulley wears and the belt doesn't ride where it should, it rides lower in the groove. The horsepower is carried through the sidewall contact in the pulley, not by it bottoming out in the bottom of the pulley groove. Throw road dust into the picture and its like polishing compound. Someone else mentioned checking the brackets for fatigue and alignment. Good idea!