Does sound an aweful lot like what @74Scooter had. What do you do for a lifter tap? Just tighten them? @MOPAROFFICIAL I have a feeler guage, whats the cardboard for, am I supposed to test them with the engine running?
If it is the lifter and the knocking does not go away the only cure is to replace it. If you can figure out which one it is that's great, you can just replace that lifter. I could not identify which lifter was making the racket and swapped them all out for new Comps. The rockers and pushrods need to come out. I was able to swap all mine out without removing the intake using a magnet on a stick. Took about an hour per side... not too bad at all.