Stripped spark plug hole
Thread Starter
Racer
Joined: Oct 2021
Posts: 436
Likes: 15
From: Maryland
Stripped spark plug hole
Hello, 82 owner. Getting done with the intake manifold gasket and spark plug job, and just found out my #3 spark plug has a stripped hole. Plug kinda tightens, but just as it gets snug, it becomes loose again. I wanna put a save-a-thread into it, but I’m at a crossroads. For the record, I’m not gonna take the head off. I just don’t have the time for it, so it’s not even an option for me.
Now, question that I wanted to ask you all, should I do it myself (I have no experience) or take it to an experienced shop that’s gonna charge $500? I am capable of doing it, but I’m afraid of messing it up. The hole is in a frankly cramped spot. Any advice will be appreciated. Thank you
Now, question that I wanted to ask you all, should I do it myself (I have no experience) or take it to an experienced shop that’s gonna charge $500? I am capable of doing it, but I’m afraid of messing it up. The hole is in a frankly cramped spot. Any advice will be appreciated. Thank you
Popular Reply
Apr 19, 2022, 07:17 AM
Race Director
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From: Sunshine Coast, Queensland, Australia
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Well, I'm a mechanic, and no I wouldn't charge 500 bucks to helicoil a hole.
There are 2 ways to do this. The right way does mean pull the head.
The cheat way is to have the intake valve open, and while blowing compressed air into the intake port so air is blasting out the plug hole. Run your tap in for your helicoil and pray that all the chips get blown out as you cut them. Install your helicoil and again when you break off the tang. have a ton of air blowing through. Most times you can get away with the cheat method, sometimes you miss a chip.
If the offending plug hole is difficult to get to with a tap.
Like it or not. off with the head.
And now is where the 500 dollar mechanic bill comes in.
There are 2 ways to do this. The right way does mean pull the head.
The cheat way is to have the intake valve open, and while blowing compressed air into the intake port so air is blasting out the plug hole. Run your tap in for your helicoil and pray that all the chips get blown out as you cut them. Install your helicoil and again when you break off the tang. have a ton of air blowing through. Most times you can get away with the cheat method, sometimes you miss a chip.
If the offending plug hole is difficult to get to with a tap.
Like it or not. off with the head.
And now is where the 500 dollar mechanic bill comes in.
Team Owner
Joined: Mar 2002
Posts: 44,678
Likes: 1,830
From: Huntsville AL
I can't speak to your capabilities so that is a call only you can make. There are a number of YouTube videos on the subject you can draw from, and the repair kit runs anywhere from $15 to $100. There is going to be some disassembly required, at a minimum you will need to remove the exhaust manifold and any other items in that area so you have good access to the bad spark plug hole.
I have never done this myself and if presented with this issue I would just pull the head and replace it, but I'm funny like that.
Good luck, let us know how this works out for you.
I have never done this myself and if presented with this issue I would just pull the head and replace it, but I'm funny like that.
Good luck, let us know how this works out for you.
Race Director
Joined: Nov 2006
Posts: 13,238
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From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
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Cruise-In VIII Veteran
Well, I'm a mechanic, and no I wouldn't charge 500 bucks to helicoil a hole.
There are 2 ways to do this. The right way does mean pull the head.
The cheat way is to have the intake valve open, and while blowing compressed air into the intake port so air is blasting out the plug hole. Run your tap in for your helicoil and pray that all the chips get blown out as you cut them. Install your helicoil and again when you break off the tang. have a ton of air blowing through. Most times you can get away with the cheat method, sometimes you miss a chip.
If the offending plug hole is difficult to get to with a tap.
Like it or not. off with the head.
And now is where the 500 dollar mechanic bill comes in.
There are 2 ways to do this. The right way does mean pull the head.
The cheat way is to have the intake valve open, and while blowing compressed air into the intake port so air is blasting out the plug hole. Run your tap in for your helicoil and pray that all the chips get blown out as you cut them. Install your helicoil and again when you break off the tang. have a ton of air blowing through. Most times you can get away with the cheat method, sometimes you miss a chip.
If the offending plug hole is difficult to get to with a tap.
Like it or not. off with the head.
And now is where the 500 dollar mechanic bill comes in.
Safety Car
Joined: Dec 2012
Posts: 3,816
Likes: 1,727
From: Summerville SC
I learned a long time ago. You always have time to do a job the right way, the second time. Aside from the fact that you already did the intake manifold, I would suggest pulling the head. Way easier to do this on the bench than in the bay. Just my $.02. Good luck. 
Thread Starter
Racer
Joined: Oct 2021
Posts: 436
Likes: 15
From: Maryland
Well, I'm a mechanic, and no I wouldn't charge 500 bucks to helicoil a hole.
There are 2 ways to do this. The right way does mean pull the head.
The cheat way is to have the intake valve open, and while blowing compressed air into the intake port so air is blasting out the plug hole. Run your tap in for your helicoil and pray that all the chips get blown out as you cut them. Install your helicoil and again when you break off the tang. have a ton of air blowing through. Most times you can get away with the cheat method, sometimes you miss a chip.
If the offending plug hole is difficult to get to with a tap.
Like it or not. off with the head.
And now is where the 500 dollar mechanic bill comes in.
There are 2 ways to do this. The right way does mean pull the head.
The cheat way is to have the intake valve open, and while blowing compressed air into the intake port so air is blasting out the plug hole. Run your tap in for your helicoil and pray that all the chips get blown out as you cut them. Install your helicoil and again when you break off the tang. have a ton of air blowing through. Most times you can get away with the cheat method, sometimes you miss a chip.
If the offending plug hole is difficult to get to with a tap.
Like it or not. off with the head.
And now is where the 500 dollar mechanic bill comes in.
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Thread Starter
Racer
Joined: Oct 2021
Posts: 436
Likes: 15
From: Maryland
Oh wow ok. From watching head removal videos I always thought that the piston intersects with the spark plug hole because it’s an interference engine. So there is no risk of the piston hitting the plug?
2026 Loser of the Year
Joined: Sep 2013
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From: New Or-leens Loo-z-anna
Place the bottom shoulder of a dial caliper against the shoulder of the stripped hole.
Then insert the "tail" of a dial caliper into the hole u til it contacts the piston...write down the measurement.
Make sure the longer plug that derek suggested is shorter than the dial caliper measurement!
Use a dab of antisieze on the threads of the new plug just to be safe.
Derek and others may know how many threads need to be engaged on the new spark plug to prevent it from being blown out of the running engine.
Of course there are risks involved you may not want to take.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
When those two do NOT avoid each other, you will witness some of the most spectacular photos in the automotive world.
A sparkplug never changes its location.
Last edited by HeadsU.P.; Apr 19, 2022 at 01:16 PM.
Thread Starter
Racer
Joined: Oct 2021
Posts: 436
Likes: 15
From: Maryland
Rotate the crank until the piston is at T.D.C. as other members said.
Place the bottom shoulder of a dial caliper against the shoulder of the stripped hole.
Then insert the "tail" of a dial caliper into the hole u til it contacts the piston...write down the measurement.
Make sure the longer plug that derek suggested is shorter than the dial caliper measurement!
Use a dab of antisieze on the threads of the new plug just to be safe.
Derek and others may know how many threads need to be engaged on the new spark plug to prevent it from being blown out of the running engine.
Of course there are risks involved you may not want to take.
Place the bottom shoulder of a dial caliper against the shoulder of the stripped hole.
Then insert the "tail" of a dial caliper into the hole u til it contacts the piston...write down the measurement.
Make sure the longer plug that derek suggested is shorter than the dial caliper measurement!
Use a dab of antisieze on the threads of the new plug just to be safe.
Derek and others may know how many threads need to be engaged on the new spark plug to prevent it from being blown out of the running engine.
Of course there are risks involved you may not want to take.
Thread Starter
Racer
Joined: Oct 2021
Posts: 436
Likes: 15
From: Maryland
What if the spark plug protrudes? doesnt it intersect the path of the piston? Sorry for asking again I'm just having trouble imagining this.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Pistons rarely enter the combustion chamber near the plug. It would have to be a "Domed Piston". And even then, there is plug clearance unless somebody put a extra long electrode in there.
Thread Starter
Racer
Joined: Oct 2021
Posts: 436
Likes: 15
From: Maryland
oh wow ok. Then I’m confused why is doorgunner suggesting I measure the distance between the hole and the piston?
Thread Starter
Racer
Joined: Oct 2021
Posts: 436
Likes: 15
From: Maryland
Also, @derekderek, how many threads do I need for it to be secure? I got a plug with 5 extra threads.
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Sorry, I would pull the head as well. It's just not that hard, a for the price of a couple gaskets.
A longer plug is a really bad idea. You will be lucky to have more than one usable thread left. And blowing a plug out while running is never a good thing.
If it's worth fixing, it's worth fixing right!
A longer plug is a really bad idea. You will be lucky to have more than one usable thread left. And blowing a plug out while running is never a good thing.
If it's worth fixing, it's worth fixing right!
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
i would pull the head as well. but OP is reluctant. he or prev owner may have been using a too-short plug when thread got hurt. it is a 462624 head. cheap and common. but these are not daily drivers. see what you need before buying parts. once one head comes off, replacing the pair must be considered. maybe ask bucaneer if any aftermarket or other replacement heads work well with crossfire. i know vortecs do not. the intake will not fit.
Last edited by derekderek; Apr 20, 2022 at 07:54 AM.