Holes in piston?????

[Bob Carriere]

What would be the most likely cause of a hole being blown through the piston top ....... occurred on a 216 and a rebuilt 261..... and the same Number 4 piston.......

Both engines are/were being used in the Montreal area..... possibly by the same set of volunteer drivers........

In my limited experience, never having blown one yet!!! ..... lugging and engine in a too high a gear for the road speed and detonation by bad timing and straining the engine from low rpm to higher speed without shifting to a better lower gear......

Can we blame the new ethanol fuel???? It has been lamed for everything else but I do not think that ethanol would cause pre-ignition....... bad timing....... bad springs/weights/ corrosion in the dizzy advance mechanisms under the main plate...... but two different engines in two different CMP trucks .....strange coincidence.

What are the opinions out there....

Curious Bob C