[Mikey]

Your original post said it increases in pitch with engine speed. High pitch noises are most often caused by metal on metal. Load and rpm on the pulley can change whether or not it makes the noise. Think about how a door hinge can squeak when opened slowly but if you open it rapidly it doesn?t make noise. I chased a very similar issue as you described for over a year that I was sure was a weird whistle in an aluminum intake pipe on my LS swap ?64 C2. The noise came and went under various rpm and load. Then the bearing completely seized and came out of my tensioner.