Spark plug thread fix

[Rich_G_SC]

Hi,

I pulled plugs the other day and a thread insert came out with #3 plug. I haven't tried to separate them yet but afraid the insert is rusted to the plug and will be damaged when I try to get if off. I have a couple of questions and am hoping maybe the answers from the community will be a PSA to other new guys who face this issue.

1) Assuming I either get the insert off or buy a new one how do I keep this from happening again? Is there a specific type of thread locker that I should be using?
2) IF I can replace the insert how do I measure to ensure I get the right one? Is it just the OD of the threads? I've seen a 14mm insert set on CIP1 - do I need to worry about thread rate or is this a fairly standard part?
3) Any best-practice general advice on dealing with inserts and heads?

Thanks very much for your advice,
Rich G.

[FVRacer21]

Rich,

I had a similar thing happen last year. Luckily, I got the insert off with heat and was able to match it up with one from Advanced Auto. These were solid insets not Helicoil. I had to grind the new insert down a bit and the kit had the proper tap for cleaning up the threads. I put it in with red Loctite and finished the season. Probably should have used green, but knew head was coming off at end of season so left it to my builder. Once in don’t try to take the plug out.

Then it went to my engine builder for a new oversized insert.

having the head off should be better as you can properly check the length of the insert and the plug.

ChrisZ

[problemchild]

I know some people consider this a "cop out" but this is a question for your engine builder. Disregard advice from online experts or regular machine shops, and ask the best FV engine builder that you know. He will have dealt with hundreds of damaged ACVW cylinder heads, and will give the best chance of saving the head. Do whatever he suggests.

[Steve Davis]

Rich,
Rollin (ButlerEngines.com) is off White Horse Rd in Greenville. Take it to him if you can. I'm not sure WHERE in South Carolina you are.
Steve

[kea]

However you fix it, in the future, use Anti-seize on the spark plug threads.

[pacratt]

I would recommend AGAINST using thread-locker on an insert...there's a good chance it will get through to the spark plug threads...and then you'll NEVER get it out.

Glenn

[FVRacer21]

I would recommend AGAINST using thread-locker on an insert...there's a good chance it will get through to the spark plug threads...and then you'll NEVER get it out.

Glenn

Many now use a plastic tool to install the insert - why having the head off is better - any locker on the threads can screw things up royally. I have also found that red loctite tends to deteriorate on heads as the temp is out of it's range. Some of these inserts are staked in place - so mechanically there is no need for loctite. With the advent of aluminum heads on street cars, repairing threads on street cars with the head on is now considered normal repair. With the VW the length of the insert is critical, it is smaller that 1/2".

Greg's advice is correct, but sometimes you are stuck at the track and have to make the call. Many times if the insert threads are not messed up and stuck on the plug -just put it back in. Threads are threads.

ChrisZ

[stonebridge20]

NAPA sparkplug repair kit.
Intake valve slightly open
Very clean shop vac blowing out through the carb to blow any chips out past the drill bit and then the tap, directly into your face.
Thread in repair insert
Swedge insert in place

I've done quite a few different aluminum heads (in the shop and at the track) over the years like this without a single problem.

[rgu]

https://www.timesert.com/html/sparkplug.html

I've used the Auto Parts store kits and they are ok. I've even done an emergency repair using the threaded insert kit without removing the head. It went a weekend.

[stonebridge20]

https://www.timesert.com/html/sparkplug.html

I've used the Auto Parts store kits and they are ok. I've even done an emergency repair using the threaded insert kit without removing the head. It went a weekend.

Every one I've done was without removing the head. That's the reason for blowing through the intake and out of the plug hole so as not to get any chips into the cylinder.

[Rich_G_SC]

Appreciate all the replies!

I am pretty sure the insert is a solid design and not a helicoil. This occurred during my race school when I pulled the plugs while chasing a different problem. I screwed it back in and it made it through 3 20min practice sessions and a short school race with no issues. I'll be reaching out to my builder for a permanent (ish?) fix.

Steve, I'm in Columbia, SC. We chatted for a bit between sessions at the DriverZ Cup race last November at Road Atlanta. Looking forward to seeing you again soon!

Thanks all,
Rich