throwing belt

[joelzip]

I have been throwing a 12 rib belt once a year for about 4 years now, its jumping forward on the car 2 ribs. I am wondering if its jumping forward on the blower while the belt is returning to the blower loose or if its jumping forward on the crank first while under tension? I cant tell because when I notice it, it has gone forward on the crank and blower, thus blowing my v-belt off of the water pump and alternator leaving me stranded on the side of the road. I am running a fixed tensioner, I am wondering if while under boost the blower is stretching the bottom of the belt under tension and the top side maybe is becoming loose as it returns to the blower. I am debating fabricating a new tensioner out of a production car tensioner that is spring loaded. The procharger tensioner is garbage as the bronze bushing wears out of it and the bracket goes crooked after a year of driving. Any suggestions? The car is an 80 malibu, sbc, carbed, d1sc with a large blower pulley, 6psi, 12 rib

[SMRE]

I have been thinking about all of this since we talked yesterday. (I am pretty sure you are the same Joel) and I think you may be on to something making your own fixed tensioner. I think you were correct that running 2 of them would help, if not solve your problem. With only running 6psi, I think we can eliminate spinning the blower too hard. It is possible that the bracket is flexing, and building a support to the shock tower would help. But, with the info you have provided I would bet it has to do with belt tension. The serpentine belts need to be as tight as you can get them. I mean you should just barely be able to get it on. We would love to see what you come up with and how it works out for you.

[mrtbolt64]

Have you ever laid a strait edge across the pulleys to see if there in alignment. I have seen to many of these bolt on kits now that have the pulleys out of alignment causing the belts to jump

[joelzip]

The blower was back in comparison to the crank about an 1/8" and I added one washer to each of the three bolts that attach the blower to the head of the motor. I'll see if it helps, it takes a summer for it to throw so I have to wait.

[SMRE]

Joel- If it takes the whole summer for it to throw a belt, and you put a new one on every year, is it possible the belt is gradually stretching or are you adjusting the tension as it does?