[GOAT72]

I have a '72 WK in my GTO.

No matter what I do to add a sealer around the threads, my #5 plug has always lost compression and it sounds like sh!t -- not to mention power loss.

I can feel the exhaust stroke flow when it puffs through the plug threads and hear a short "pfsssst" sound each time. I've used different sealants to deter the loss of compression, but it only works for a short time.

My brother is a truck mechanic and he said to use a helio-core to rethread the plug hole. Sounds easy enough, but Milt Schornack told me to pull the head BEFORE I do this because if a shaving gets down into the cylinder I'm screwed.
I really hate to pull the head if I don't have to...

Any suggestions?

[pggto]

The only way I know to fix that is exactly what your brother told you. You will need to install a heli-coil, and you don't want to risk getting metal chips in the cylinder.

[GOAT72]

I can think of several advantages I'd gain by removing both heads - including the need for new exhaust manifolds, but I found this on the Web:

The concern that most techs have about doing a thread repair on a spark plug hole while the head is still on the engine is metal chip damage. Any chips that remain in the cylinder after the hole has been drilled and tapped for the insert can easily cause cylinder wall or other internal engine damage. The key is to control the chips before they have a chance to get into places where they don't belong.

You've probably heard of coating the drill and tap threads with grease to capture the chips as you work. Alternately, you may wish to fill the cylinder with shaving cream before beginning the work. The shaving cream places the chips in suspension. After the work is completed, turning the engine over slowly should force the cream and chips out through the spark plug hole. Clean the area thoroughly before continuing.

A shop vac can also be used in reverse for chip control. Duct-tape the exhaust end of your shop vac to the tailpipe, then crank the engine over until the affected exhaust valve is open. Turn on the shop vac, then begin your drilling procedures. The shop vac s exhaust should propel the chips out of the cylinder as you work. Wear eye protection to shield your eyes from stray chips.

Has anyone done a HeliCoil with the heads on?

[Ron Landis]

pull one head without even removing the intake, why do it the hard way? Personally, I'd pull both and get a valve job done as well. Good luck. Ron