I have a 91 Mustang w a 331 stroker motor. Everything in this motor is brand new and blueprinted to spec. I recently found that my distributor had come loose and was causing a lot of detonation and misfire from the dist. moving back and forth. I set a timing light on it and set it to about 10 to 12 degrees base timing. After tightening the distributor down and double checking timing the motor runs fine. However when I blip the throttle by hand I can hear a rattle noise occur. When I put my hand on the valve covers no noise felt. When i put my hand on the distributor I can feel the rattle come right up the distributor. I have no idea what this could be. The roll pin in the gear on the distributor is nice and tight and the wear marks from the cam are nice and even. The only thing I can think of is the water pump bearing went bad??? But its a brand new water pump. Any advice or suggestions before I rip the intake and valve covers off to check the rockers??