Having issues with belt squeal on my factory AC unit - I'm pretty sure it's coming from the alternator. Basically bring the revs up to 3300 - 3500 and the screeching starts. Hoping someone has some idea or trick I haven't stumbled on to.
Pretty much a factory setup except I think a 69 compressor. I've spent quite a bit of time aligning the pulleys including adjusting the pulley on the alternator, shimming the alternator mount - using straightedges and a length of 1/4" straight tubing laid in the pulley grooves. I decided the factory alternator mount with the long spacer was just too loose and bought a new one that is solid between the alternator lugs (no spacer tube). It was not a lot better but after doing some bushings and wrapping the bolt to tighten up all the looseness the alternator to mount was solid.
Mounting it to the block I found the whole alternator still tilting slightly in towards the crankshaft laying a straightedge on the alt pulley - just as the old mount did. So I put a couple of shim bolts behind the two inner bracket mount bolts and that seemed to put it pretty straight as one of the pictures below shows. I also pulled the alternator pulley out about 1/8 inch to get it lined up as close as possible with the crank and AC comp pulleys.
I bought a new set of belts from Quanta and applied CRC belt dressing to them and set the whole thing aside for a week and then installed them. They sent me 44" belts which puts the adjustment towards the far, outside end of the adjuster strap. That's what their charts showed for this year. I had 42" belts on it before and they adjusted towards the inside of the adjustment slot. I may drop another $70 and get some 42 inch belts from them if nothing else seems to work.
I replaced the alternator and pulley a couple of years ago and I'm wondering if it is somehow the issue. The belts seem to ride a bit high on it and the outside, wide edge of the new belts measures .380 vs .373 on the worn ones. the inside, narrow side is around .213 on both.
I've tighten the bezezzes out of the belts - probably about 1/4 deflection on top with finger pressure at mid-span. Hasn't seem to do any good except cut down on belt flap some. Finally resorted to thumbing through my shop manual (the instructions) and for some reason they have adjustment specs (deflection or torque) for every situation except a 383/440 with AC. Great.
Basically, I have a 3500 rpm - max 440 at this point. Above that and it's just a loud screech that sounds like everything is going to fly apart. Don't remember having this issue when I bought the car years ago and the one thing that has changed is the alternator and pulley so I'm suspicious of it.
Any body got any ideas or tricks to try - beyond getting some 42" belts, maybe look for a different alternator pulley, getting a longer piece of 1x2 for a pry bar to tension with?
Pretty much a factory setup except I think a 69 compressor. I've spent quite a bit of time aligning the pulleys including adjusting the pulley on the alternator, shimming the alternator mount - using straightedges and a length of 1/4" straight tubing laid in the pulley grooves. I decided the factory alternator mount with the long spacer was just too loose and bought a new one that is solid between the alternator lugs (no spacer tube). It was not a lot better but after doing some bushings and wrapping the bolt to tighten up all the looseness the alternator to mount was solid.
Mounting it to the block I found the whole alternator still tilting slightly in towards the crankshaft laying a straightedge on the alt pulley - just as the old mount did. So I put a couple of shim bolts behind the two inner bracket mount bolts and that seemed to put it pretty straight as one of the pictures below shows. I also pulled the alternator pulley out about 1/8 inch to get it lined up as close as possible with the crank and AC comp pulleys.
I bought a new set of belts from Quanta and applied CRC belt dressing to them and set the whole thing aside for a week and then installed them. They sent me 44" belts which puts the adjustment towards the far, outside end of the adjuster strap. That's what their charts showed for this year. I had 42" belts on it before and they adjusted towards the inside of the adjustment slot. I may drop another $70 and get some 42 inch belts from them if nothing else seems to work.
I replaced the alternator and pulley a couple of years ago and I'm wondering if it is somehow the issue. The belts seem to ride a bit high on it and the outside, wide edge of the new belts measures .380 vs .373 on the worn ones. the inside, narrow side is around .213 on both.
I've tighten the bezezzes out of the belts - probably about 1/4 deflection on top with finger pressure at mid-span. Hasn't seem to do any good except cut down on belt flap some. Finally resorted to thumbing through my shop manual (the instructions) and for some reason they have adjustment specs (deflection or torque) for every situation except a 383/440 with AC. Great.
Basically, I have a 3500 rpm - max 440 at this point. Above that and it's just a loud screech that sounds like everything is going to fly apart. Don't remember having this issue when I bought the car years ago and the one thing that has changed is the alternator and pulley so I'm suspicious of it.
Any body got any ideas or tricks to try - beyond getting some 42" belts, maybe look for a different alternator pulley, getting a longer piece of 1x2 for a pry bar to tension with?
