Quote:
Originally Posted by xtn
Well I havn't taken a camera to mine yet, but it looks pretty much just like that.
Notice the faint bluing of the cast material on either side of the crack? I suspect this has something to do with localized heating? Possibly the area begins flexing, gets too hot, work hardens, becomes brittle, and then finally snaps off?
Maybe. Even if I've got that sequence correct I don't know where it all falls into place relative to the cam lobe wear.
xtn
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Hell yes, it's the heat. The oil should be pouring directly onto the high-lift cam--because the rocker-arm pad on top of the tappet catches a whole lot of friction, and otherwise dissipates the heat only through its loading spring--but the spray from the camshaft cover on (at least) intake #3 is misaligned.
Hot, hot, hot. I'm wondering what might happen when the tappet expands into the space where the packer pin gets shoved under it.
I followed Badnis' lead (from exiges.com), who simulated oil flow from the overhead outlets in the camshaft cover -- to see if his results could be replicated and confirmed. I've got lots of pictures from the test, and will post them in a follow-up thread.
Update: link!
In the mean time, here are some more shots showing the damage in my head
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