[HWYSTR455]

The PS belt DOES ride lower in the pulley groove than the alt belt normally. (Look at attached pics) And you should be running a 15 series belt. When changing to a different series, it's not only the width that changes, it's the angle of the sides of the belt too, so if you run a belt that's not for the pulley by design, it will slip. I'm running a 15485 (48.5 inch) and it works great. Worn crank pulleys (or damaged pulleys) will slip. If the belt has ever slipped, it's toast and needs to be replaced. Post a pic of your pulleys and bracket setup.

I believe I'm running a '68 setup, with a 69+ timing cover and water pump. With this setup, 7k is no problem without slip.


.

[HWYSTR455]

Ah, I see now, you have the 69 setup. Are you using the same aluminum piece on the head as I am as it appears in the pic I just posted? You may be able to just change your water pump, or use the 70 pulley. Like I mentioned, someone pointed out that 69 is a one-year only setup as it pertains to the water pump.

http://forums.maxperformanceinc.com/...=69+water+pump

http://forums.maxperformanceinc.com/...=69+water+pump

.

[Cameano]

Well, after reading that second thread you posted, I'm under the assumption that I have the '71 and up setup on the car. It looks exactly like the stuff pictured. It also looks exactly like the spare set of brackets and pulleys I have off of the '72 GTO I parted out last year. (For those wondering, you needed a tetanus shot to go near it, it had sat close to the ocean for a few years taking salt air and rain on an almost daily basis. ) I'm going to clean up the spare pulleys in the blast cabinet at work Tuesday, see if they make a difference.

[HWYSTR455]

And that's a xxxx127XT pulley you have?

[chiphead]

Just for Reference: 11 bolt water pump is '69-newer. Your upper alt bracket is '68-earlier and missing a piece (strap to water neck). The PS bracket looks to be '68-earlier as well but hard to see in pics.

I had horrible V-belt squealing/tossing issues I couldn't solve: No belt, alighnment, pulley, tension, etc combination would work. Wide-belt, narrow-belt, ribbed, non-ribbed, lubricated, KY-Jelly, nothing. The belt would squeal, turn over in its groove and throw rubber everywhere.

I went with an underdrive pulley from summit and all the problems went away. I installed in in place of the stock alternator pulley. Only downside is it reduces alternator output at idle. FWIW...

[HWYSTR455]

There's 2 diff 69 11 bolt water pumps, a 4", and a 4.5". That's what I'm thinking is part of the problem here. The bracket actually looks post-70. pre-70 I believe used only straps. Regardless, as someone in another thread said, you can replace the 4.5" with the standard 4", as long as you replace the water pump pulley.


If you want to call someone who knows about pulley setups, call ram air restorations. They did their' homework prior to offering replacement billet pulleys, and can give you part numbers of the pulleys, what water pumps to look out for, and bracket info. I believe BOP Engineering can do the same.

.