Last winter I had the 396 out of my '68 chevelle rebuilt and modified from 325hp to 418hp. It was bored, stroked, decked, heads milled, etc. I had a hydraulic roller cam, roller lifters and rockers installed. Shortly after installing it I was getting some gas and when I restarted it it had a loud tapping noise that went away in about 30 seconds. I got it home and checked out everything I could, but since it wasn't making the noise now I couldn't find anything wrong and it was running fine. I put 1000 miles on it with no problems. Then. a few weeks ago I was out cruising and the noise suddenly came back as I was driving and isn't going away. It's not there when the engine is cold, but as it warms up the noise starts to come back and gets louder as it gets warmer. It sounds like a single cylinder. Using a stethoscope I believe that it's #1 or #3 cylinder. I've adjusted the valves several times with the engine running and it seems to quiet down for a few seconds but then come back. I'm using 10 w 30 oil. The oil pressure is around 65psi cold and 35psi hot. I believe, and hope that it's a faulty lifter but wanted some other opinions from more knowledgeable people. Searching this site for noisy lifters it seems that everybody else's problem is that they're noisy when cold and then quiet down as they warm up where my problem is the opposite. Which makes me think that maybe it's a bearing or something else that is the problem. All opinions will be greatly appreciated.