WTF is this sound???

[ChargerAndy]

Since I got the car it has always made a sound when it revs up to what Im guessing is about 2800 RPMs and stays untill the revs go down again. I have changed the water pump and I have disconnected the Alternator and the sound is still there. The engine performs well and there is no performance difference when the sound starts. It is really hard to pin point since there since it's so loud at that RPM but it seems to come from the passenger side..... I thought for sure it was the alt but no. The sound is like shrill static....and if I had to try and reproduce it I would putt a handfull of gravel in a tin can and spin it in a drill while shaking it as fast as I could. I would really like to correct this but Im not sure where to go from here. The engine is a 74 440.  Dudes, Ive ignored it for awhile but not it's making me nutz    Could it be the distributor? or the valve train?  Help! Andy

[John_Kunkel]

Check to see if the harmonic balancer ring is hitting the front cover.

[ChargerAndy]

I just garaged it accross town from me, so I'll check that, but, I ran into a buddy of mine and he said check the viscous clutch fan. Anything I do will have to wait till next time I get her out, but, would the fan make a sound like that

[Just 6T9 CHGR]

Stock exh manifolds?    Could it be the heat riser flap making noise on the pass side manifold?

[dodge freak]

You can take all of the belts off and start in up for a 1/2 min. to see if it is one of those items the fan belts drive, it quick and easy to do. If its is gone start put one belt on at a time until the noise come back. Yes the exhaust can make all types of noises so that is another place to look at.

[ChargerAndy]

Stock exh manifolds?    Could it be the heat riser flap making noise on the pass side manifold?

Non Stock..... headers are on the vehicle right now. I would have to say it does sound like its coming from the front more than the back.

[1970440RT]

     The words I use to describe detonation is " rocks in a tin can ".  It is a very difficult sound to describe.  If the noise happens only at 2800 rpm and over, I would tend to think this is what it is.  Check your timing and back it down a little or disconnect the vaccuum advance to see if the noise goes away.   Another thing you can do is upgrade the fuel to see if it the noise disappears.  Slight detonation may cause overheating, if the detonation is audible, it is very bad and can cause severe engine damage.  I would find out what it is asap.