Grinding, " diesel " noise under valve covers

Virgin bore 340, old trw forged slugs.. funny you say that.... ran her, checking timing curve...came in about 7.... 2 hours later was still warm under hood. Wond6er if she went in heatsink...155 psi cylinder pressure when I checked during the timing fiasco. And what's wrong w/ a dingelhone? I used one on my Ironhead drag bike....a 240 or 280... left a nice cross hatch...besides, if you used one, they can't be all bad!