A few days ago my step-dad and I finished swapping my 305 TBI to a 350 TBI. It has sounded fine, but today while listening to it it began making this whistling noise. It didn't start until the engine had ran for about 5-10 minutes, and we're not exactly sure what could be the problem. If I turn the car off and wait a bit, then turn it back on it doesn't resume the noise right away. I recorded a video from my phone (sorry for bad quality) and captured the sound. Any help is appreciated.

http://www.youtube.com/watch?v=UcXtaoR8PQo

New video that shows my exact problem: http://www.youtube.com/watch?v=o9wNM-3f9W4

 

Pay attention to A/C, alternator, tensioner.

Just a 2cent guess, sounds like a bearing in 1 of them is bad.

 

I apologize I haven't been able to reply for awhile. We've narrowed it down to the transmission area, but we're still unsure of what it is. I have found a video of exactly what my problem sounds like and such.

http://www.youtube.com/watch?v=o9wNM-3f9W4

 

Check vacuum lines.