Ive had the same belt (113) that cam with my vortech kit for a while now. I swapped to a smaller pulley (3.12 from a 3.33) and used the same belt. Since the cam swap the belt has squeeled, but not before . I took budhayes3 advice and used some valve lapping compound on the belt and the squeel is gone except for a few times when the converter locks up at low speeds and it starts squeeling real loud for a minute or until I get into it and then its gone. Im now thinking that the belt may be too long and the slack is allowing it to misalign just a bit every now and then and causes the squeel. Im going to go to a smaller 2.87 pulley when I get my fuel trims in order. If I do need a new belt, how much smaller should I go? I also changed out the A/C tensioner so I know that isnt it. Im just a little lost as to why it squeels now and not before the cam swap. We used an air hammer to get the crank pulley lined up again, so everything is good there.

 

with my old procharger kit my belt started to squeal when idling and very low speeds. it was after the last time i had pulled my motor out and really didnt know why it was doing it ...slip was never a HUGE issue but it had normal slip. a little blet dressing every couple of weeks took care of it though i was using a good year gator belt...u also might want to try Katech's fixed tensioner....

 

i ran the 113 belt on my powerdyne with the 2.93 pulley,
when i switched to a 2.70 pulley the belt was to long, had to go with a 110, then i changed to a 2.50 pulley and on that one i had to go with a 109.
good luck on finding the right belt, i know our systems are not the same.

 

So that belt dressing stuff actually worked for you? I may switch to a 109 and see how that does. I guess I'll get some dressing as well. I really didnt notice any slip until the cam swap and subsequent belt squeel.

 

the dressing worked for the squeal..it shut u.the slip was kind of always there but like i said never to bad....

 

Where does your factory tensioner mark point? (theres 3 index marks to tell you how much slack you have)

 

its back I took everything apart a few weeks ago and saw that the bolt had backed itself off a bit or we didnt tighten it enough. I hit it with the air gun to get everything aligned and then put some loc tite on it. The day I did the LS1 fans it started squeeling again. Belts are all perfectly lined up. It seems to get substantially quiter as I drive it, but starts squeeling badly when I get into it. I took a look at the 3 marks for the tensioner and I am just to the right (driver side) of the middle mark so maybe my belt isnt too loose? Im at a loss. I already replaced the AC belt tensioner that is notorious for this. It seems to make up to 2 lbs less now than when it wasnt making the squeeling.

 

Assuming a 50% belt wrap, the 3.33" pulley used 5.23" of belt.
With the same belt wrap, the 3.12" pulley uses 4.9" of belt

So the new pulley has a .33" smaller amount of belt to use.

That does not seem like it would make much of a difference. Maybe others with Vortechs could chime in for you.

 

Smaller belt is in need. I know that my brother had to go to a smaller belt on his mustang when he changed to a smaller pulley on his YSi trim. Also email Vortech and ask them.

 

If it's to the right of the middle line, then I doubt you'd be able top get a smaller belt on there. Mine stays right on the center line, and it's pretty tight.