chirping '95 z28

[z28ed]

My z28 is making a loud tap-chirp noise that is in sync with my timing light flashes.I thought it was a collapsing lifter (it may still be),but when I turn the engine off,it makes a whistle-ending sound.As the rpm's go up,the noise becomes a destinct tapping as if it were a lifter.With a stethescope,the sound comes from deep within the engine,more on the passenger side.I have heard of Impalas making a similar noise with a sticking valve problem,but mine did it before and after a valve job(and with stiff Isky springs).My Flowmaster exhaust is as loud as the chirping noisez28ed-chirpie.