power valve makes my 440 ping??

That C clip is damaged if you look closely!! What looks to be happening is... you don't have enough preload on the lifters & the cup is slamming into the clip, this will cause it to bend & pop out, you need at least .020" preload on those style lifters, are you running an adj. valvetrain? On all my Mopar engines i build anymore with aggressive cams i always run adj. rockers & Pro-magnum (anti-pump-up) lifters with the E clip (lesson learned), they are designed so you can set them at "0" pre-load if desired.