Greg:
Since you asked if anyone had this happen in their experience, yes I did
many years ago. I was racing an MGB at the time which is quite similar to
the Healey in many ways I hope you do not have the same problem, but it
sounds similar. I was racing and the engine was under quite a lot of
stress, so I would think that this would be rather rare.
The piston crown had separated right below the rings. The top was moving up
and down without the constraint of the connecting rod. When it was pushed
up it went up to the head and wiped out the tip of the spark plug. It is
amazing how these engines can continue to run with all sorts of damage. I
believe the cylinder was firing occasionally while the spark plug was still
functioning. I think a broken wrist pin or something similar could cause
this problem also.
I found the missing plug tip and thought it was just a bad plug. I put a
probe like a screw driver down the sparkplug hole and found the top of the
piston. However when the cylinder was at bottom dead center, the top of the
piston could be pushed down by an inch or two showing it was no longer
connected to the crank.
Gary Smith
64 and 66 BJ8s
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