wierd engine noise, help would be appreciated

[bransonfink]

After putting a new head, valves and cams on my 93 240SX and putting everything back together as it came off she started right up, but have a shreak whisle. At first I thought it was a drive belt, but if you increase RPM's the noise increases and actually squeels at you, this noise is steady. I tightened all the belts, taking into account diflection. I still had that noise. I decided to take each belt off, start the engine and see if that eliminated the noise. After taking each belt off and having no belts, no moving pulleys, I still have that noise. The noise does not increase with RPM's, matter of fact it some what decreases from 1800 - 2200 RPM's. Above or below the noise is the same. I used a stethascope and tried to pin point the area but can't seem to narrow it down. I have a feeling unless someone has had this problem or has a suggestion, I am doomed to take the car apart to find the problem. If anyone else has run into this problem any help is appreciated

[Michaelmoore]

Just a small guess, but maybe you have a vacuum line somewhere that is kinked a little and causing the air moving through it to whistle.