[kdavies3]

Hi Wilf,
my best guess is that it was the increased cylinder pressures created due to the faultering ignition timing, combined with the detonation I had at Elvington on the track.
The piston top land looked like a mechanical failure as opposed to being melted in typical detonation style.
The piston was also cracked thru the 2nd land and all the way down the skirt.
Oh boy was I lucky to get away with driving it home the 250 miles.
I could easily have totalled the engine.
I'll be giving it a run to Silverstone tomorrow.