With a lower power, all motor car.. I wouldn't have an issue using a helicoil, or a time sert for a plug hole.. But get into a higher power, power adder setup.. Then you may find issues. The plug dispels heat from the chamber/cylinder into the threads of the head. When you use a helicoil or time sert for this, you may have one cylinder (your repaired hole) that does not transfer enough heat into the head as the other plugs that are going right into the aluminum.

Food for thought.

 

I thought about what you said and talked to them about this. They said that since the insert is made from aluminium as well, it should not affect the heat transfer from the plug...hmmm I guess we will find out in due time...

 

Momofx, how's the repair going?

 

Not saying they do not exist, but I have never seen an aluminum helicoil. They are usually a chromenickel steel.

So I don't know what they are using, but I would be curious to know.

 

If the head is off the motor, the ultimate fix is to drilll out the plug hole, and weld in an aluminum slug and drill/tap it for the plug.

 

I would not over think this. As someone else mentioned, Ford DOHC guys routinely did this on their motors without issue. I just did this on a brake caliper fitting where the brake line connects which is under significantly more pressure than a spark plug. You don't really have anything to lose. If it blows out then you have to replace the head anyways.

 

Haha, I confess - I have a "bad" habit of doing that

 

So I got the Time-Sert and installed it. It is a very nice kit btw and comes with quality stuff and everything to do the repair. Instructions are straight forward and to the point (no chinglish thank God). Basically you re-tap the damaged spark plug hole with a slightly bigger tap then you install the correct size insert for a GM with a special tool it comes with and its done. I seems very stout and I should fire her up soon (still finishing up the engine oil cooler setup).

This is exactly how it works :

 

The only thing the video failed to mention regarding installation is to be sure to clean out the threads prior to installation to make sure you don't have shavings in the hole.

 

I think they assumed someone using this kit would naturally do that lol I did not even think about that when I was doing it as I used some air to blow it out and then when I was done I just blew the whole head out with some air to be safe

 

If we are talking about Time Sert, only some of their inserts are aluminum. Their standard inserts are steel. Another issue with inserts on LS heads is that, unlike DOHC heads, the inserts don’t match up well to the inside of the combustion chamber. You tend to get a messy, sharp edge from the enlarged hole. And the insert does not extend all the way through. This can be largely cleaned up with a small file if the head is off. But if it is done over the hood without removing the head, this could be an issue in terms of creating detonation-promoting hot spots.


This is a spark plug hole in a 243 head that has been rethreaded with a Time Sert and filed to make it cleaner.



For comparison, this is a spark plug hole on the same head with good threads.



This is the repaired hole with a spark plug.

 

Oh yes I remember cleaning it up a little. So far so good