rhoads lifters?
I had a set in a 360 in my 77 Dodge pickup with 284 cam. When the weather was cold they clattered like crazy until the needle on the temp gauge moved. The engine had good oil pressure at idle and especially when cold. They would even occasionally clatter when it was warmed up. Checked and re-checked my adjustable rocker arms. Solution...put 'em back in the box and place them in the attic of my garage. I replaced them with some PAW lifters which were quiet and I didn't notice a bit of difference in performance.