Unsafe FIRE engine?

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Unsafe FIRE engine?

Jul 8, 2005
on the A684
Can a FIRE engine become unsafe (as far as the valves are concerned) if the head is skimmed excessivly? I ask this because of reading about an american non-interference engine which got buggered up when the head was skimmed and the camchain snapped.
Would think so yes.

Apparently theres skimming marks on the head to indicate the maximum point the head can be skimmed to from the manufactured specification.

I believe these are around 30-50 thousands of an inch from standard. At this point the engine would become interference.
It can happen to any engine. Most of the times when the timingbelt snaps is because it has aged, used for too long, material weakness, seized tensioner etc.

But it can also happen due to a valve spring breaking, which I had once in the workshop.

As tom said there is maximum skimming mark. But it is safe to go slightly over this mark.