The other day after I started up my car I noticed a wierd noise coming from under the car, I stuck my head under there and it seemed like it was a noise coming from the engine echoing through the exhaust of course. So I took a small piece of 2x4 and stuck on end on my driver's side valve cover and my ear to the other end (a trick my dad's friend Mike Janis taught me......btw he was Pro Mod Champ in IHRA in 2003) and I hear this wierd chattering noise that is in rhythm with the noise I heard from under the car. My two assumptions are a loose rocker or something to do with one of the rockers or a bent pushrod. Anyone else got any ideas on what this could be and how to fix?

 

Since the Driver's side valve cover is the easiest to remove, take a peak under there and at least eliminate problem with the valve train.

And as Robvas mentions, spark plug, manifold, etc.

 

It looks like it might be spark plug related. Took it to a friend of a friends place who had a OBDII Code check thing and it threw codes for multiple spark plug misfires, bad mass air flow sensor, and a couple other things due to me not getting the car tuned since I put the headers on.