Valve guides, rockers, various crush washers and gaskets. I
would suspect an oil problem developing in the cylinder
heads allowing a little wear on the valve guides and or
rockers. I'd check to see that the oil supply lines are not
blocked.

The different copper alloys used can allow determination of
what part is contributing the metal, since different alloys
are used for different parts. Contract Lycoming and have
them look at your results, they can give the best answer.



--
James H. Macklin
ATP,CFI,A&P

"Peter" wrote in message
...
|I have now been to a few engine rebuilders, including one
who designs
| and builds engines from scratch (not aero engines) and
overhauls all
| the normal kinds of aero engines, and he reckons this
doesn't mean
| much. The IO540-C4 has brass bushings around the rockers,
and few if
| any other brass parts, and the main bearings are not
brass.
|
| Interesting...