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Stripped Spark Plug Hole
Posted by: BritCars ()
Date: September 30, 2009 10:30PM

Recently I've found the new spark plug wire [Clark''s] on the #4 cylinder popping off a couple of times. I assumed that because of the awkward location under the throttle shaft, I just had not pressed it down correctly. Since I had driven a couple of miles before checking out the problem, I thought I should remove the plug and see if it needed cleaning.

Bad move!

When I went to reinsert the plug - which was clean anyway - I found the plug would not screw into the head. There seemed to be no bite from the threads. A call to Ron Moller of Maplewood Motors (Maine's professional Corvair resource) confirmed the worst, that the head was likely stripped. I tried to chase the threads with a borrowed thread chaser, but it did not help.

I searched here for advice and found a kit that offered a slightly different solution.

I didn't want to just putty the plug in and wait for the problem to arise again, so I pulled out the wallet and called a mainland CarQuest. They had a Heli-coil product kit entitled a "Spark Plug Thread Repair." It consists of a thread cutter [14 mm] that attaches to a 3/8 ratchet, three different sized coil inserts, and a drift to complete the insertion. Lastly, they require that you purchase some RTV [high temperature], which I fortunately had at home.

The kit came on the 12:30 ferry and I got to work. The thread cutter was the right length so I could use a long extension as a "straight edge." I put some grease on the threads and began the cut. I took it slow and took it out a couple of times, cleaning the threads before reinsertion. A friend who is an out-of-work machinist helped guide me, as he's done this sort of thing often.

When I got it deep enough, we cleaned out the hole and inserted the coil. The instructions tell you to run some RTV around the outside of the coil, and use the spark plug as an insertion tool if necessary. So I did and was relieved when the plug came out by hand with the coil holding firm.

Then you take the drift and keeping it straight, whack it a few times with a hammer. That seems to crimp the upper coils against the thread. I put the plug back in and torqued it down. It felt very smooth threading into the head.

The RTV compound wants 15 hours of curing time so I will have to wait until tomorrow morning to see if the heli-coil holds and the car runs fine.

Assuming it really works, this kit seems to remove the need to drill out the head first as it provides you with a hand tool that seems to work great in aluminum alloy. I suppose it would be a lot harder if the head were steel.

Just wanted to share this (potential) solution.

Jeff

Jeff Aronson
Vinalhaven, Maine 04863
'66 Corvair Monza Coupe 110 hp 4-speed
'66 Land Rover Series II-A 88" SW
'66 Land Rover Series II-A 88" HT
'80 Triumph TR-7 Spider
'80 Triumph Spitfire
[www.landroverwriter.com]
[www.dirgocorvairs.com]
[roversmagazine.com]

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Re: Stripped Spark Plug Hole
Posted by: RAV_AIR ()
Date: October 01, 2009 01:31AM

Nice move, Jeff!

"So where do they put the engines in these things?"
"They put em where they belong....in the rear."
No More Vair :-(
Topeka, KS
Moderator

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Re: Stripped Spark Plug Hole
Posted by: Spectre ()
Date: October 01, 2009 01:07PM

I've used that same kit before. Works very well.

David Clamp


1965 Corsa convertible - 140 4spd/3.55/AM-FM

2013 Mustang GT convertible - 5.0, 6spd auto

2003 Miata SE - 6spd manual (wife's toy)

"Victory is mine!" - SG

Warner Robins, GA (15 miles south of Macon)

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Re: Stripped Spark Plug Hole
Posted by: patpaldino ()
Date: October 01, 2009 01:09PM

I've wondered about those kits...good info, thanks!

'65 vert ~ Worcester, MA

SOLD!

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Re: Stripped Spark Plug Hole
Posted by: BritCars ()
Date: October 01, 2009 02:39PM

Well, I've had 2 miles of carefree driving this morning, so the "Sav-A-Thread" kit from Heli-coil seems to be working.

David, I'm relieved to hear that you've used the same kit and it's worked for you. Ryan and Pat, thanks for the good wishes!

I won't be able to put on much mileage before Saturday's 50th anniversary celebration in Brunswick, ME, about a 120 mile round trip from this island. Thanks to Ron for arranging it with Goodwin Chevrolet. The owner has told me that he's quite the Corvette buff, so I'm hoping he stops by.

While I had the car on downtime, I also took the time to rebuild a suspect wheel cylinder on the right rear. I've been losing fluid from somewhere and that wheel cylinder was the only one to look wet and gooey when the drums were off. The Clark's kit worked perfectly and I think [hope] that I got the cylinder cleaned up properly.

So far, I have brakes, but I probably need to bleed them again.

Jeff

Jeff Aronson
Vinalhaven, Maine 04863
'66 Corvair Monza Coupe 110 hp 4-speed
'66 Land Rover Series II-A 88" SW
'66 Land Rover Series II-A 88" HT
'80 Triumph TR-7 Spider
'80 Triumph Spitfire
[www.landroverwriter.com]
[www.dirgocorvairs.com]
[roversmagazine.com]

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Re: Stripped Spark Plug Hole
Posted by: patpaldino ()
Date: May 12, 2012 07:09PM

Jeff, has it still held up? Same thing happened to me just today on my #5 cylinder...guess I'll be doing the same thing you did...

'65 vert ~ Worcester, MA

SOLD!

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Re: Stripped Spark Plug Hole
Posted by: irfgt ()
Date: May 12, 2012 07:55PM

I use the kit all the time.I have never had a failure. You actually have a better thread than original.

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Re: Stripped Spark Plug Hole
Posted by: patpaldino ()
Date: May 12, 2012 10:39PM

Good, I just put one in mine! With any luck I'll be swapping motors out next year anyhow... smiling smiley

'65 vert ~ Worcester, MA

SOLD!

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Re: Stripped Spark Plug Hole
Posted by: LesH ()
Date: May 12, 2012 11:48PM

My '63 has been running around as a summer daily driver since 2000 with a Sav-A-Thread in Cyl #1. No issues at all.

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Re: Stripped Spark Plug Hole
Posted by: vairmech ()
Date: May 14, 2012 10:55AM

My only problem with the kit is using the RTV. It is an insulator and will change the heat range of the spark plug slightly. Maybe not much but maybe enough for those hot days when it will make a difference.

Just be mindful of what you do with the air cooled engines.

Ken Hand
CORSA Central Division Director
CORSA Treasurer
248 613 8586
[www.corvairmechanic.com]
vairmech@aol.com

[s186.photobucket.com]

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Re: Stripped Spark Plug Hole
Posted by: jimmyo ()
Date: May 14, 2012 11:05AM

When using these kits, is there any concern about bits of metal falling into the cylinder?

Jim O'Connor
45 miles north of The Bronx, N.Y.
1962 Greenbrier 110 4spd
1964 Monza Convertible 110 PG
"Wherever you go....There you are"


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Re: Stripped Spark Plug Hole
Posted by: dryenko ()
Date: May 14, 2012 11:55AM

I have used a similar insert in the distant past, and it will work once, IF you use some antisieze on the new plug threads when installing it.
However, there is a better than 50-50 chance that the insert and the plug will come out together the next time you pull that plug.
Using some red Locktite helps , but even that stuff, over time with heat , loses it's effectiveness.
The only true fix, IMHO, is a Time Sert [TM] which gets swaged into the aluminum of the head with a special tool for sealing and locking purposes.
I have been usingh these on street and race heads without subsequent issues since they I discovered them in the 1980's when the inserts you have used gave me problems.
As always , YMMV
BC

Bob C
Dobson, NC
Zip 27017
1965 Maroon Monza "110" 4 speed Autocrosser
1965 Corsa Conv Street/ Track/ Show car with semi-cage
1966 Corvair Crown 327 V8 4 speed w/ AC [under active restoration]
YS 172 SCCA GT3 semi tube frame road racer
El Lobo tube frame all Corvair Street Buggy [ resting comfortably, needs engine ]
Manx lookalike Buggy , EM Corvair rear suspension/ VW bug front suspension -RUNS !!
Daily drivers : E250 Ford window van w/ built 460, 2005 VW GTI 1.8T
And a few other toys

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Re: Stripped Spark Plug Hole
Posted by: patpaldino ()
Date: May 14, 2012 12:53PM

Bob, thanks. I am almost certain if I have to pull that plug that the insert is coming out with it too...but hoping this will get me by at least for this summer into fall. Plans are to put a 110 into my car after this year...

'65 vert ~ Worcester, MA

SOLD!

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Re: Stripped Spark Plug Hole
Posted by: curt ()
Date: May 14, 2012 03:27PM

I have used Heli Coil on an iron head, workrd fine. The lwn mower shop placed one in a lawn mower with and AL head, it worked fine.

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Re: Stripped Spark Plug Hole
Posted by: MrChips ()
Date: May 14, 2012 06:11PM

I wanted to have my heads time-serted, but the machine shop used 'Keen-serts'. Similar in function, but they are locked in place by 4 inserts that are pressed in, so you can technically remove them and change out the insert if you ever have a problem with the threads etc.

I don't thing aluminum threads for spark plugs are a great idea - especially since the plugs are removed / replaced frequently on many engines.

Thanks again to Dave and Phil for putting my heads in the workpile (grin).


Where Santiago and Live Oak Canyon intersect in Orange County, Ca

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Re: Stripped Spark Plug Hole
Posted by: Ray W ()
Date: May 16, 2012 03:37AM

This is a timely thread for me, unfortunately! The wifes Caravan had been running rough. Was pretty sure it was ignition since it was worse when damp out, and would get better when warmed up. I picked up a set of wires, and since the flaps had a deal on plugs if purchased with wires, I got those too. Last night I swapped out the wires and then went to change the plugs. The plugs hadn't been touched in 20k miles and almost five years. The first one to get the wrench just spun, even though it had been installed with anti-seize. The heads are alum.
I really, really don't want to pull the head. So, the Heli-coil sounds like the deal. My only question is, how do you be sure to tap the new threads straight? This looks like a real trick with the plug hole recessed out of the way on this v-6.
I guess I do have another question. The stripped plug doesn't move in or out, just spins, but does turn with a bit of resistance. The van runs great with the new wires. The other question is, what are the odds of the plug just staying put while the wife just motors on? The other plugs, (they are platinum) are like new so this one should be in good conditition too. If it were my ride I would just drive it, but my better half, you could say, gets flustered when unexpected things happen when driving.

Ray W

Minneapolis

66 500 Coupe 95/4spd

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Re: Stripped Spark Plug Hole
Posted by: patpaldino ()
Date: May 19, 2012 06:14PM

Well guess I didn't do a good job putting mine in...drove it today, pounded it on a little bit and at about 50-55 it blew out on me sad smiley Never happened to me before but for some reason when I heard the loud pop I knew what it was...

'65 vert ~ Worcester, MA

SOLD!

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