[1968GTO421]

Originally Posted by ZeGermanHam

Just want to take moment to apologize for the awkward formatting of my post above. For some reason, when I add a photo as an attachment to a post using my smartphone, that's what happens. Looks normal on the phone, but is all kinds of screwy when viewing via PC. I'd edit it to fix, but can't do that anymore.

Your post #14 looks fine on my PC. no problems viewing it (I appreciated the detailed photo.)

[dataway]

If it's at exactly the same rpm I'd bet it some kind of belt flutter or resonance that effectively loosens the belt temporarily. Possibly a pulley ever so slightly out of round or eccentric on it's shaft.

I've always wanted a (pretty expensive) variable strobe light for watching things go wonky when they are moving fast.

If it's some kind of resonance problem then changing the tension on the belt should shift the rpm where it happens.

I guess the other solution might be the fan clutch doing something unusual at that specific rpm which cause it to dump a big load on the belt (figuratively speaking of course)

[TedRamAirII]

Hook your timing light to the coil wire, strobe!

[Tarl]

So, haven't had time to get over to the the shop until last night. Checked pulleys with straight edge and they look pretty good to me. I then removed the fan and fan clutch and tossed the belts back on, lo and behold no squeal.

So I learned my lesson about the SD clutch a while back (due to all the time loudness, not the squeal) and put a HD clutch on my firebird. I may swap that onto my lemans and see if it still squeals.

Appreciate all the help!