Running excessive valve clearances can also cause a valve to break.

The last part of the camshaft profile lowers the valve gently onto the valve seat. If you have too much clearance the valve is dropped onto the seat by a much more aggressive part of the cam lobe. The additional loading can eventually crack the valve stem and pound the seat.

 

BTW, you should clean your catalyst when you install a new engine. Don't forget.
A lot of debris is blown in the exhaust. As you can see in the intake manifold.

 

I will be gone for a week so I can't check anything further until then. But, I will definitely check the valve clearances when I get the chance.

I'm not accepting that the engine can't be run at high revs. I refuse to believe a properly designed engine by a respectable company would be assigned a redline below which it would break apart. It goes against everything I've ever learned, and everything I've ever seen....

....except, of course, this one as-of-yet-unresolved small detail of my engine.

 

This made for one hell of an interesting read. I am leaving this thread with more knowledge than I came in with. Sorry for your loss.

 

Lsos Posted on Nov 18 2009, 09:38 AM
The valve clearances chris_barry is talking about are between valve stem and rocker (and cam).
Without a cam that is hard to check.
But I guess you know that

You can check the "play" in the valve guide, if possible also where the damage is, with one of the other valves.
Maybe remove the seal first to feel less resistance.

It could be "just" a bad valve.
Sometimes, the valve stem and valve disk are 2 different materials, they are friction-welded together.
I don't know if that is the case with F20/F22 valves.
It sure does look like the valve sheared at the point where the weld would be.
Just a wild guess.

 

They are two different materials, the face is not magnetic and the stem is.