81 300sd, 280k, wvo but ive been running mostly diesel. just checked the valve adjustment job I did last week, as I've done a long road trip and wanted to make sure I did it right (it was my first time doing the valves). There were 4 tight ones, and all the others fell within spec. Some were harder to get the feeler gauge through than the others, and I've just had a hell of a time getting them adjusted to the perfect gap which is why there is this slight variation. Anyways they are all correctly gapped now.

Side note: the reason 4 were out of spec was that last week I thought I made them too loose because the engine was running rough. Turns out it was just air in the lines.. Oops!

So I'd been meaning to fix the tight ones and just today got around to it. She fired up fine, and I drove her maybe 500 feet before a slight knocking appeared, which got louder as the rpms increased. It is quite a loud and prominent knock that I have definately never heard before. First thing I thought was low oil but it's fine. I had just driven her about 400 miles yesterday and had no signs of a knock or any engine noise that was out of the ordinary. So my question is: are the valves too loose? What could I have done that would have caused this? All I did was adjust 4 tight valves. I'm afraid to drive the car until I get this fixed. The car sat for about 9 or 10 hours (overnight) before adjusting the valves today. I'm planning on letting it sit in it's current location till tomorrow before trying to readjust them.