Installing sparkplug inserts in aluminum head

[oleman]

Product: Thread Repair Products
Summit P/N 900190
The tap is stamped perma-plug 2258-14 (probably the mfg of the Description: Description: 14MM X 1.25 X ¾ thread restoration enlarging tap for a threaded spark insert.

Use: Replace stripped out threads in a engine head

Procedure: Use enlarging tap to create a new hole for a threaded insert to replace a stripped spark plug hole in an aluminum head.

The story:

I have years of experience and a well lighted shop area and any tools required.

I got the SUMMIT plug hole restoration kit and 2 additional plug inserts to repair the threads in a pair of aluminum heads for my current engine rebuild.

I have pictures that I took with my elcheapo digital camera but they are very low quality and only usable for things non precision.

The tap:
The idea behind the tap is that you will thread the tap into the existing spark plug hole which will center it. Then you continue to drive the cutting tap down through the head and create new threads for a slightly larger threaded insert.
Problems:
This only worked if the existing threads are in good enough shape to allow enough torque to drive the threading cutter. 2 of my holes went fine the third hole was stripped to the point where the cutter cut a new hole that was slightly off center creating a slight angle for the spark plug. Actually I believe it was always off center, great quality control.
The tap is 5/8 hex drive and requires a very thin socket to clear the head on most modern engines
They recommend starting the tap by hand and then continuing to drive it with a ratchet or other driver, this will tend to make the hole produced go off center unless you are very careful. A much better solution would be to use a large TEE handle to keep the tap square.
While making the cut many chip are produced, do not totally remove the tap to clean chips, because it could be very difficult to restart, back it up a few turns, blow the chips away and continue to cut.
The tap has no gage or stop, it?s strictly a guess as to how far too tap.
If you do not tap all the way through the insert will stick before it is totally in.

The threaded inserts:
The idea behind the threaded inserts is that they will be threaded into the new taped hole and create a new thread for the spark plugs. High temp RTV and swaging is used to seal and secure in the head.

Problems encountered:

They recommend using a spark plug to install the threaded insert. This does not work very well because the plug to insert is a closer tolerance than the insert to aluminum head. The threaded insert will stick to the plug and get removed when the installing plug is removed. This is especially true of tapered seat plugs. I solved this problem by using a scribe in the combustion chamber of the head against the threaded insert when removing the plug.
The threaded insert is very soft, do not attempt to hold the threaded area with pliers or you will quickly bugger the threads.

The threaded insert protrudes into the combustion chamber of the head. Now there are extra threads to create hot spots. Probably a die grinder should carefully be used to shape the insert out of the way.

The threaded inserts are held in using a knurled end and swaged with a swaging driver that you are to hit with a hammer. In this process you are driving a metal insert against the aluminum head. Not good for the head. You probably should support the underside of the insert some before swaging it.

OPINION:

I would not be surprised at all to find the insert stuck to the plug the next time I change the spark plugs.

Installing 3 plug inserts took over 2 hours plus the price of the insert kit. In the future I will only add the inserts to special heads. Standard old stock heads are not worth the time, effort or money.

This is absolutely not a job for someone without experience, tools and a good place to work
It would be impossible to install the inserts in an engine without removing the head because many chips will end up in the combustion chamber.

Ther are probably other important issues but this is it for now!

[sharkey]

RE: Installing sparkplug inserts in aluminum head

yea ive done this many times before. ive even done it a couple times on gen 2 motors on the back head in the center hole, when its still on the car.

[geoffinbc]

It sounds like a higher quality kit might work better. Something from HeliCoil company might be better.

Who Knows

[imported_germ]

i will NEVER use one of these EVER again.

im on insert #3 on cyl #4.


i had one come out when i replaced the plugs the first time after putting the insert in.

then 2 weeks later, the insert and the plug (still attached to the wire) blew out of the head on the on ramp to the free way. thought i blew something up and i wasnt even gettting on it, just speeding up to highway speeds.


since then, ive taken it sorta easy and only boosted hard a few times and i now have another set of heads that i have to port and polish and put springs on

[oleman]

Was the one that blew out the same as the ones I used from SUMMIT? I have that write-up with pictures but can't post it because it is a word doc.
Based on my experience, the insert is a way to make a repair to reclaim a head that otherwise would have to be junked.
I do not see the insert blowing out unless all the threads stripped out of the head. The threaded insert has a larger diameter than the normal plug so has more thread area but anything can be stripped.
My opinion is that it would unscrew with the plug if the plug ever really stuck to the insert. When reinstalling with the head on the engine it would be very easy to strip out the head, then it becomes trash.

The reason I personally went with the inserts is because I spent $88. surfacing the heads and later discovered one spark-plug hole was not too good. I could have bought JW heads for less or about $30. each.

[bszopi]

Send me the Word document (bszopi@60degreev6.com) and I'll convert it to PDF and get it online. Or convert it to html and get it online. Either way, I'll get it online.

[oleman]

More issues with the inserts.
I installed plugs with the heads off the engine, good thing!
When I attempted to torque them to 16 Foot Pounds the inserts screwed themselves on through the head on 2 of 3 inserts.
I backed the inserts out and re-rtv't them and reinstalled, this time I was careful to stop with about .010 on the topside. I removed the installing plug and peened them with an 18 oz hammer and the swaging tool.
I retried the spark plug install, this time they held in place to install and remove torqued to 16 foot pounds.
I am hoping that when the heads temperature cycle the inserts will become more secure.

[sharkey]

i personaly have always used green loctite (the sleave retainer stuff) on inserts. once the stuff is hard, there is no moving the insert.

[imported_germ]

Was the one that blew out the same as the ones I used from SUMMIT? I have that write-up with pictures but can't post it because it is a word doc.
Based on my experience, the insert is a way to make a repair to reclaim a head that otherwise would have to be junked.
I do not see the insert blowing out unless all the threads stripped out of the head. The threaded insert has a larger diameter than the normal plug so has more thread area but anything can be stripped.
My opinion is that it would unscrew with the plug if the plug ever really stuck to the insert. When reinstalling with the head on the engine it would be very easy to strip out the head, then it becomes trash.

The reason I personally went with the inserts is because I spent $88. surfacing the heads and later discovered one spark-plug hole was not too good. I could have bought JW heads for less or about $30. each.

no, the kit i used was a different brand, but the idea is the same.

tap out the old threads with the provided tap, screw insert onto sparkplug, put on some type of locking additive to the threads, insert into head.

as long as the insert itself is aluminum, then its pretty much the same kit (idea).

the threads of the insert stripped out when the plug blew out. the insert was still attached to the plug. i retapped the threads to clean the locktite off of the threads.

i have had to change the insert everytime i have pulled the plugs. dont count on the insert staying in when you remove your plugs.

i have tried many locking additives to keep the insert in the head, all of them work fine if the car has not be ran and heated up. once its gone through a heating cycle or two and you try to remove the plug, the locktite crap just gives out.

im not sure if there is anything that will keep it in there for good, aside from welding the insert or doing some type of "compression" on the tip of the insert and seating it into the head somehow.

these are the locking additives i have tried.....

jb weld
red locktite
red off brand locktite (worked better than the real stuff)


currently, i am using antisieze because it allows a clean removal of the insert when i need to remove it. i just recheck the plug and re-tighten as needed if it starts to come loose. ive been using antisieze for about 3 months now and only re tightened twice i think. so its not to bad.


i will be switching over the heades soon, i dont want to take the chance with the insert since ive had nothing but issues with it.