Topic: Stripped spark plug hole fixed w/ oversized adapter

[Tugboat]

I'm working on a CB350 that someone (NOT ME!!) stripped one of the spark plug holes on. They have used some sort of oversized adapter in the hole, which I'm sure would be fine if I could get it to stay. Instead it comes out with the plug and I'm not sure I can remove it from the plug without messing up the threads. I figure I'll get a new one and properly insert it so that the plug can be removed independent of the adapter.

However, I've never done this before and am not sure how you're supposed to get the adapter to stay in the head. Anybody done this before?

[iron_worker]

By adapter do you mean one of these:

http://www.helicoil.in/

or these:

http://www.timesert.com/

If so, then you you'll probably need a new one with the insert tool. Hopefully your insert threads have not been damaged.

IW

[Muckinfuss]

here's a third choice for what you might have:

http://www.ezlok.com/InsertsMetal/carbonSteel.html

[bollingball]

For sure go with the timesert much better than a helicoil for a spark plug. If you take your time and prep everything you will not have a problem with chips. I put the piston up to the top then stuff a coil of of a strip of rag soaked in oil but not dripping into the hole till full leave the end so you can reach it later with needlenose or hemostats to pull it out when done. All the chips will come out with it. Before you pull out the strip of rag I go around with a vacuum I make a small adapter that ends up with a 1/4" hose if you snag the rag just start pulling it out with the vac. Before all of this use grease on your cutting tool to collect any chips you can during the cutting of new threads and clean and renew the grease every so many turns. Better safe than sorry.
Ken

[Muckinfuss]

Ken, it might be possible, or even more desirable in the long run to use whatever it is that came out, but with a high grade thread locker on the replacement.  This way he's not cutting a hole with a tap that has different thread count and profile from the original insert that was used before.  Tapping over top of what's there could result in shot head if there's too much difference.

[Duanob]

If the plug is a 14mm thread then helicoil makes a plug insert just for this purpose. It was made specifically for ford F150 aluminum head 4.6L and 5.3 motors. Its not a typical helicoil as in it has a knurled edge and lip at the top to stop it from going in too far and to grab the aluminum casting and not let go once installed. I had to install one on my Ford and I put about 20K miles on it with no problems. I'm sure it would work on a honda head if the threads are the same.

the timsert kit was spendy, the helicoil was about $35.

[Tugboat]

^I think that's what is currently in there. Some of the threads towards the top are knurled and I figured that's what they were for... keeping the insert in. Maybe they just didn't install it correctly?

And yeah, I was hoping to just use the same type of adapter/insert and not have to re-cut the threads. I'd considered using red Loctite but doesn't that come loose with the application of heat? What sealant can I use then?

[Muckinfuss]

Permatex High Temp Thread Sealant.  Any auto parts house should have it. at about 10.00 per tube.  The two High Temp Loctite products are over $40 per tube.