Keep in mind a belt will walk 'up hill' not down hill as most would believe.
In other words....to track a belt, you lift one side/end of a roller and the belt will track/move towards the lifted end..the tighter end.
Is your idler bracket on a slight angle?
Just a thought.

 

Got them, thanks. For the record, maybe to save someone the trouble of reading through 3 pages, the part# to the 100mm pulleys are MIP-100, and 90mm are MIP-90. The bearings are part# 6207.

I spoke to Jason @ Magnacharger, he suggested I loosen the manifold and it will move back and forth a bit. I think I'll try the pulleys first, clearance in a car with the J-tube is minimal

 

Ok, I got my pulleys on today. For the record, the part# stamped in the bearings was 6203, not 6207. Also, I have the new design of the supercharger bracket, and second spacer did not have to be machined. its cast into the bracket, and also both pulleys required a washer behind them to space them away from the bracket, or they were rubbing. now that its all together, I want to post a pic of the belt.

When you look at the drivers side idler, belt is in line with supercharger/idler/alternator, but the passenger side tensioner and idler, the belt is a little bit forwards, marked with a yellow arrow on the pic. is this normal, or is something wrong? Tensioner is new as are now both pulleys...HELP!

 

Looks like a problem to me.
Looks like your whole SC needs to move forward to bring everything into line.

 

How do I move the sc forward, its a part of the intake?

 

I had a slight misalignment at that same spot on my setup. Had you turned the motor over when you took that pic? if not, give the belt a few cycles and see where it ends up, you may have a bad tensioner

 

That pic I took after a short drive, so thats the way the belt ends up. I loosened the whole intake for ***** and giggles, and used a ratcheting strap to put some tension on it pulling forwards, while i tried wiggling. That did absolutely nothing, after i bolted everything back together, the front snout support sits in the same spot it sat before.

How would I know if I had a bad tensioner? I got it from magnuson direct, that and the belt, along with the new design front bracket.

 

Does the belt stay on now?

 

i tried 3 times and it stays on, i have my fuel pressure goes down under boost, I have a brand new walbro255 in the tank. I have about 44 at idle with vacuum, 58 with vacuum off, but as soon as boost hits pressure drops to 40psi...I dont understand why one 255 isnt enough, I am looking into an external pump right now.

 

I had this EXACT same problem with my install. I too installed Moregrips 100mm pulley upgrade and had a lot of belt squeal. The passenger side idler was not parallel with the other pulleys. With a straight edge I could see that this pulley was turned in towards the tensioner,the same way as yours. I gave this to my brother(a toolmaker) and he carefully gaged it up at work and found that the passenger side idler bracket surface was not milled or ground "parallel" with the Tensioner mounting surface on the magnacharger supplied bracket. It took a while for him to set this up on a mill for rapair, but once aligned it took less than 5 min. to refinish. I think he ended up taking .009" off the right side of pulley surface while just grazing the left side of surface. All pulleys are aligned and quiet now.

Also the passenger side Metco idler pulley hit on the pulley bracket just like yours is doing now. I had my brother remove some material from the inside back of the pulley(on a lathe or mill) and that fixed the problem. I also had him cut down the front of both pulleys for a better look(as per Moregrips advice again).

Thanks for doing all the leg work on this one Moregrip!

I hope this might help.