After many belts, washers, shims and many choice words I installed the March underdrive pulleys and the squeeling is gone and the belts stay on. V belt pulleys, the alt voltage is still 14 at idle and my cooling has not been affected. My Ac however has considerably higher head pressure at idle, the 20% drop or so in airflow makes a big difference at idle. Going down the road no big deal.

Figured I would share the info, I chased this problem for a while.

Thanks for sharing your fix Scott.

What kind of pulleys did you replace?

Replaced water pump and crank pulleys with March under drive units. Solved my belt throwing issues and squeeling. $200 is kind of steep but I spent almost that much in belts...

What kind of pulleys were the ones you took off?

I tried stock (that had a bunch of miles on them), chrome ebay specials before the march units. I had all kind of throwing/ squealing issues. DOn't know if the reduced speed or the deeper groove solved it but I'm happy to drive it without the belts coming off. Was mostly the alternator belt.

How much under driven are your pulleys?I just installed 30% under,and it's o.k. for the most part,volts and temp.,but it got warm with me doing some test n tune yesterday getting ready for the track,hot lapping the car.SBC V belt kit I got from Smiley's was water pump,crank and belt for $80.Haven't been on the highway yet with this set up,had a similar crank pulley before and it was o.k.

20% underdrive