valvetrain noise 5.9 magnum

Well I just recently pulled my carburetor off to send it off to get some bushings installed on the throttle shafts because it was causing a pretty big vaccum leak. I do have an old edelbrock with worn out throttle shaft bores on the shelf that I could bolt on just to get it fired up and record it idling with my camera . I just don't know if you guys would be able to hear it on a video but it's possible, It kinda sounds like a tapping noise, kinda has the same sound as if you took a screwdriver and used the plastic end and tapped on the valve cover but its not extremely loud, and it seems to go away once you give the engine some throttle.
And I was under the impression that nothing under the valve cover are adjustable, but I have read that the mopar rockers suck, I don't know what this is but it kinda has me concerned. I haven't noticed any difference in performance from the engine, it still runs strong still has good oil pressure and the compression is still real good.