just out of curiosity have you dumped the initial oil from the rebuild? I don't suggest running the engine with rocker covers off, I do suggest removing the rockers and closely inspecting the tips for abnormal wear can also check for a collapsed lifter by pushing the rocker downward into the lifter, you should not have the strength to compress
I am fairly certain that it is not torque converter bolts loose. Also, i re-torqued the header bolts but they werent loose, so doubt if leaking exhaust.
Yes, I have changed the oil and filter recently... I didnt notice anything in the oil, but, i didnt strain it either.
I will recheck each rocker to see if i can manually compress one... and then remove the rockers and look for any abnormal wear... If that all negative, i guess it is time to try pulling each lifter and examine... Ive never pulled lifters with the intake manifold on, so going to buy an extractor and give it a try... Ill start on cylinders 8 and 6 as to my ear it sounds like the back cylinders. Still a mystery to me, as, it doesn't sound like a normal valve tick, but more of a "clatter".
Thanks for the suggestions.