Quote: If the aluminum isn't from bearings maybe its from the biggest piece of aluminum on the engine, the W5 heads. I would look close at the spring pockets in the heads.
I plan on tearing them down to give them a close look... but I cut them down in the spring pocket for drain back which you have to do on the W-5s but that was a couple years ago.... nothing jumped out at me when I changed them to larger valves
