Heil-coil Spark plug

[ST. RACE]

I have a plug thats real real tight. I think the threads will come out with it.
Will a heli-coil hold up to high boost,if so can i do it on the car.thanks for any help.

 

[OldGrayII]

Realistically, the head "Should" come off to do it right!!

 

[2FAST4U]

Don't hope for the worst just yet. I would try soaking the plug down with some PB Blaster first. Spray and let it sit for a while and then soak it again. I've had some good luck trying this in the past on stubborn plugs.