It may be pieces from the timing chain guide assemblies. You'll have to remove the front timing cover to verify this. If that's the case, then the timing chain probably skipped several teeth which may have caused several valves to get bent.
Thanks rogoman. I combed thru the timing chain section of the FSM... the parts blowup diagram ... but couldn't see anything that looked like this piece. Went to the mechanic's today & examined the timing chain assemblies - nothing. Surprisingly, I thought it was a pretty simple setup.
Anyway, I forgot to say in my earlier post that he showed me a spark plug with no gap from cylinder #2 ... said the piston was hitting the electrode. He even put it back in after opening up the gap, put it back in & started the car. Idled nicely and then he revved the engine & soon enough it stalled again with the same clunking sound. Took out the cyl#2 plug & it lost its gap again.
I mentioned he had checked the piston con rod bearing yesterday ... found nothing wrong. So we really don't know why the piston is hitting the plug. Today, he screwed on another rocker cover. Showed me mine, and pointed to the plastic seal rings that lined the holes thru which the high tension cable connect to the spark plugs ... he said they were disintegrating and bits had fallen into the combustion chamber and may have caused the damaged to the plugs. Huhhhh ????
Anyway, started the engine with the diff rocker cover, revved the engine up to 5k. Repeated few more times. It seemed to work ... we examined plug #2 & found the gap intact!
I still think there's something wrong somewhere down there in the piston-crankshaft connection. Perhaps I'll take it to another mechanic for a second opinion.
Btw, he also changed the upper timing chain tensioner. He's not familiar with the B14 & there I was with the FSM in my Android phone showing him how to align the 3 sprockets of the timing chain
