BuiltAmericanTough

So the other day I was doing some routine maintenance when I noticed right away that there was an unusual new sound coming from the engine, loudest being near the distributor and ignition coil. Both of which are aftermarket MSD brand, wondering.. and hoping for repair cost that one of these could be the culprit. To me it doesn't sound like an engine knock or ping. Maybe lifters? Not sure what that would sound like. I'll attach a link to YouTube where I uploaded an audio recording of the sound which I can best describe as sounding like a miniature sewing machine if you could imagine that... I apologize for the crappy quality it was the best I could do at the time. If anyone has an opinion I'm open ears!
http://www.youtube.com/watch?v=OlaCq62YGLo&sns=em