Technical spark plug hole thread repair

Need advise; has anyone repaired spark plug hole threads while head still on engine or should I pull head? this is for a 8ba

 

Check with this company https://www.timesert.com/
I have used them, no issues, & easy.

 

Taking it that this is an iron head this is the way I would do it on your engine with the head on. Bring the piston to the topof stroke, though you might have to take it down a little if the tap hit it. This is to try and keep any swarf in one place. Put plenty of grease on the tap to catch as much swarf a possible. Once tapped put on of those little magnets on a extendable stick down the hole to collect any stray swarf. Repeat process with piston bottom of stroke. Then put in insert.

 

What @brading just said.

I’ve used both Heli-coils and thread sert for spark plug repair.
Both work well , I prefer the thread sert.



greasy drill bit by hand to catch the shavings.
Greasy tap by hand to catch the shavings.
Then magnet down the spark plug hole to catch any strays and you should be good.
Bit going by hand with grease on your tool, most of the shavings should sticks to the bit and tap.
Done lots of spark plugs in aluminum heads and ohv engines like this with no issues.