Hi-
I have posted these videos over on a Healey forum, but I respect the amount of engine knowledge on PP very much. So perhaps someone here has a few thoughts.

The engine of my mom's 1966 Austin-Healey 3000 BJ8 makes a ticking sound which is troubling me very much. The sound is most noticeable at idle. It is a ticking or clicking sound, at the same speed as the engine. I have adjusted the valves twice (0.015 inches cold the first time and 0.012 inches cold the second time) and it hasn't changed the noise. I have filmed the engine with the valve cover off, so I am hoping someone can help me figure out the problem.

Both videos are at idle, although I don't recall if the RPM was slightly elevated because the engine wasn't very warm. I think the loud clack is pretty obvious, but let me know if you aren't sure what noise I am worried about:
https://youtu.be/nAYgH7i2atQ

This second video used the iphone's slo-mo feature. It is actually pretty cool because you can align the noise (now muffled, but clearly louder than the other noises) with the valve movements. At 0:24, you can see that the noise aligns with valve 1 and 3 starting to open. At 1:45, the same noise aligns with valve 8 and 11 closing up. I have no idea if these sorts of noises are more commonly associated with opening or closing of a valve.
https://youtu.be/Cfv1scOIiwk

Before I filmed any of this, I used a mechanic's stethoscope to try to find the problem. If I had to guess, I think the noise was towards the back of the engine. I had trouble getting any more specific than that. But this does make me think that valve 8 or 11 are more likely the culprit than 1 and 3.

Nothing else looked awry in the engine, but I am not very experienced with these cars. I checked the pushrods by rotating them and they all seemed straight. There seemed to be plenty of oil pooling up there, but I guess I don't know for sure. British cars do have less oil up here than some other vehicles, I believe.

The engine was rebuilt 4000 miles ago (17 years ago), but the car has only been driven 200 miles in the last 10 years. So it may have developed some problems due to lack of use.

Also, when I received the car, it had a lot of rust on the underside of the valve cover. The valve cover rust was worst at the back of the engine. It was flaking off and small chunks were landing on the valve train. Clearly this could cause damage which might cause the noise. I tried my best to clean off all the rust and wipe away any chunks, but who knows what happened before I ever touched the car.

Anyway, sorry for all the background info, but I wanted to provide it in case it is helpful. I guess my main request is for someone to watch the videos and let me know if you recognize that noise. Thanks so much for any assistance you can provide. I really need your help with this one.

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1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).