My first guess would be that the clutch throw-out bearing is touching up against the clutch fingers.
You can confirm this by running the engine up until you hear the noise, then slowly step on the clutch peddle. If I am right, the noise will go away before just before you get to the point where you can feel the clutch disengage. You can practice this maneuver whit the engine off so you can learn to "feel" the way the clutch acts. My 284 makes this noise sometimes and I don't consider it to be anything wrong.
I haven't posted enough to be able to include a link to my web page where you can see a file about 284