Hey guys, I'll give a little back story on my build then copy and paste what I had put in my thread on the Forced Induction Section. 71 Dart Street/Strip. 360 block bored .060 over with a 4 inch crank making it 414 cubic inches. Aluminum Indy T/A heads. This was built for boost so its right at 9:1 compression. Running a Procharger with 10 lbs of boost. Blow through carb. See below for what happened. Okay guys, the last pass I made down in Alabama the car slowed down a bit. I had hot lapped it so I didn't think much of it. The Next day when I was unloading the car off the trailer it was missing. I pulled the plugs and the #5 cylinder's spark plug looked like the picture below. Ground strap had been punched into the electrode. I borrowed my friend's bore scope and there was evidence that something had been in the cylinder but was no longer there. We checked the compression and it was good, same as the other cylinders. Can't figure out what could have gotten in there. Carb looks normal, hat, ect. I checked every tooth on the procharger…. everything looks good. I checked the vale lash and all was normal. So, I thought it must have somehow sucked something in that cylinder but then spit it out the exhaust valve. I swapped to colder spark plugs and have been driving on the street a few days with no problems. However I have been driving like miss daisy not getting on it. Since racing season is over around here I decided to get on it yesterday to see if I still have problems. Sure enough, heard a pop on the 1-2 shift and shut it down. It was missing. Limp back to house and once again my #5 plug had the ground strap mashed into the electrode. Any ideas? If it were the piston hitting the plug would the scars on the piston be in the same place? Could something still be in that cylinder I just haven't seen it with the bore scope? You would think if something were in the cylinder it would be loud at idle. This thing sounds completely normal at idle and low RPM. I'm baffled. I'm going to bore scope it again but If I can't find anything I guess I'll pull the engine back out and inspect everything.