29ft rear gas pusher RV with 440 about 1976 vintage engine open chamber heads, standard bore. Bought this thing a couple weeks ago, has about 5k on 15yo engine build. KB hypereutectic pistons probably about 10:1 not sure- VERY few miles on the build, because it quit on him and then he left this world shortly after. So I tear it down and there's a burned piston just ONE all others look just fine so I figure it was a vacuum leak or a fluke and replace the piston. Runs fantastic for about 200 miles, then it burns ANOTHER ONE, right next to the one I replaced. Again, no other pistons show sign of pre-det that I can see. Sooo, anyone have any ideas here? Seems to me that the compression is just too high for 92 pump gas and stock timing, and It's a new carb/distrib too. What I can't understand is why it's taking out one piston at a time (adjacent pistons) with others not showing any signs of damage? Any thoughts appreciated please see photo.
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