I am stumped on this problem,i picked up this 68 RR a couple of weeks ago and drove it home about 150 miles on back roads running anywhere from 35 MPH to 65 MPH and had no problems in the engine.

However i developed a sound in the motor area that sounded exactly like a Fan belt squeal or alt bearing squeal and changed Alt with one from NAPA and also changed belts..still there after the change!

So next thing i thought Water Pump,Changed that and still squeals..

So i was stumped again and thought OK lets try it w/o any belts on P/S and Alt...Still squeals..

Now Finally i am done for a few days with it,so i put in a OIl Prssure Gauge to Keep an eye on Pressure and on start up it is almost at 80LBS and as u can see in Video Here starts up fine and no squeal.
I was using the old hose trick to find any small unheard squeals in engine compartment.This is a Cold start from overnight sitting.
http://s1260.photobucket.com/albums/ii566/twinscrew698/?action=view&current=IMG_2129.mp4
Sorry about the video Quality and whistling sound as i was working by myself and trying to get the IPHONE to sit up by itself.
Then as u can see after a few minute warmup it started to squeal in this video.
http://s1260.photobucket.com/albums/ii566/twinscrew698/?action=view&current=IMG_2130.mp4

Then after about ten minutes in this video.
http://s1260.photobucket.com/albums/ii566/twinscrew698/?action=view&current=IMG_2131.mp4

I have been told a few things that could cause this but figured i would see if any one else has had this happen to them!
Any help would be helpful to me if you can!
Thanks