I had my TR 6 engine rebuilt several years ago, I started it and run it on a test stand , then I started assembling the body and frame over a year long process, I installed the motor and started it but noticed what I thought was a loud valve train, I adjusted the valves a few times but the noise persisted. After inspecting the rockers and shaft, I noticed they were the original ones with cupped rocker shoes and galling on the shaft. The shaft had ridges making it difficult to remove the lifters. I bought a new shaft, rockers and checked the pushrods, installed and external oiler. i started it up again and the same noise no matter how many times I adjusted the lash. I checked the lift on the pushrods with a dial indicator and noticed the first lifter was out by .030 . I pulled the head, took the cam out and noticed some wear but not that much, however I did notice that the oil had 60 grit size metal pieces in it. The lifters did have some wear due to the fact that some of the old rockers were not distributing any oil down the pushrods. before I took the head off I ran the engine while pulling the plugs to check the noise but the tapping or knocking still persisted. I am going to pull the pan and inspect the lower end and the wrist pins as well as the crank. Any suggestion as to what is causing the noise would be apprecelated.