TF Coil pack

Changed the spark plugs and found that the screws holding in the coil packs were not working. A PO had stripped the thread in the head.

My question is, should I leave things alone or put in an appropriate helicoil insert in the head. Would there be enough meat in the head to take a helicoil?

Suitable precautions will be taken when drilling and tapping; tape over the spark plug holes, vacuum cleaner during the work.

I would say if everything was working fine before, I don't think I'd bother. Whilst I know it's great to have everything spot on, sometimes you can end up creating problems when to just enjoy the car is the prime thing

+1 for that.   Unless the coil pack is so loose that it's bouncing around and loosing contact with the spark plus (incredibly unlikely) then just work around them. And, if they really are bouncing and rattling then you can anchor them down with appropriate thickness pieces of hard plastic to sandwich between the tops of the coil packs and the top cover.. Fear not.

One thing you might consider is to cover the screw thread with silicone releases compound / silicone grease, just a smear, then mix up some epoxy two pack. Give the thread form a REALLY good, clean, them dibble the epoxy into the screw hole. A good stir to ensure you have the gloop down to the thread root, then try to find the original thread & finally insert the screw & walk away.
An extra spot of hardener will accelerate the process if you’re impatient, or you can warm it with a heat gun.
The long route I feel is always the best with adhesives.
M

On that basis, I will leave well alone.
It is well to a degree; no misfire on start up but a random non-smoothness when idling.
I was thinking of replacing the coil packs but it is driving satsifactorily. So will leave well alone.

What about loctite and fix a stud in place, then use a nylock nut?