ORIGINAL: Ralphbf
Or I could put some loose power in an envelope and send it in the mail, News at 6 o'clock.
No need to hurry. We can meet some day anyway.
ORIGINAL: Ralphbf
What do you think of my version of your drawing?
That's exactly what I ment - in my drawing there was a flange - just hardly can see that, as jpg compression took it away

This flange would be used to also to tighten the insert in the head. A little tool-wrench something like 1/4-28 screw driving the insert from the insideshould do the job.
I'm not affraid of insert falling of when engine is running, but I need to prevent it from unscrewing while you tighten the glow plug.