Okay guys I recently just built a sbc 355 and it's been running strong for about 5 days now, I started to hear this faint noise inside the engine bay, now it's louder and gets louder the mkre throttle you give it, to me it sounds like it's comming from under the valve cover , I have not noticed a loss of power, it still idles smooth runs smooth and shifts smooth any ideas on what to try?

 

A noise that keeps getting louder as time goes by can be a concern. For a simple thing to start with, what valve lash procedure did you follow?