Spark Plug Problem?

Still working on the 280SE Coup. I did indeed have a dead thermostatic valve on the injection pump. As well as an incorrectly set point. It was barely opening. A couple of tight intake valves but no big deal. runs a bit better, but still not perfect.

I did however, find a fly in the ointment. #6 spark plug, is somewhat stripped out. it will run flush with a little bite but it will spin if you try to put any torque on it. Somewhere along the line it looks like it has been over torqued. The cylinder will fire without a miss but I don't think that will last. How can I correct this problem without removing the head? I don't think it could be tapped and heli-coiled with the head on, the chips would get in the cylinder. Any suggestions?


Mike
61 220 SE
69 280 SE
72 250C