Re: Hole in piston
I agree with the suggestions of old degraded fuel, and possible ignition advance issues. Either may cause detonation damage.
The somewhat surprising thing to me is..... that you damaged only one piston.
Ditto having the distributor tested, or better yet, replace it with new, and go with electronic triggering.
Rick ... aka Ricardo..... AQ series Volvo Penta repair
28' SDN F/B w/ twin Volvo Penta 5.7L DP's
Please... no PMs!
I would prefer email .... jenery (at) aol.com