Fixing a stripped thread

[BNCHIEF]

I have stripped threads on the head in my car it is the distributor hold down screw I did not think i overtightened it but it will pull when you tighten the jam nut. I know about heli-coil but do not like that idea as much as using a thread-sert, so it will be steel and epoxied in place looks like a good solution have not checked yet but I believe the thread is 3/8". Ideas and tips appreciated. thanks

[Patrick]

Oversize [ 1/2X13] studs are available.

[tbirdtbird]

I think this is the dizzy hold-down screw., the one with the jam nut.
Over the years ppl have jacked the crap out of the jam nut, that is how this happens.

If the head is off, a helicoil is easy to install, but not so much on the car.

3/8" is .375, 10mm is .3937

I have successfully carefully used a 10 mm tap as a fix while the head is in the car, then blue loctite the 10 mm bolt in place, and forget a jam nut.

There are 3 different pitches to metric bolts, I forget which pitch I used, but it was the one that most closely matched the SAE pitch that was already there. Just hold a 3/8 fine thread bolt up to each of the three metric sizes and you will immediately see which is the best choice.

Of course be careful of the chips!

BTW what is the diff between a helicoil and a thread sert? Not familiar with that. Got a link?
I find helicoils easy to use and in this case I would red loctite it in

[BNCHIEF]

http://www.wurthusa.com/web/en/websi.../time_sert.php I think this is better than a heli-coil T-bird your thoughts?

[BNCHIEF]

This is what I am thinking of doing. 3/8 fine thread do you know what pitch i will figure it out this seems to be best on an open hole repair in stainless steel. The threads already were jacked in my head and are only gonna get worse.

[tbirdtbird]

not sure how that is different from a helicoil....what comparison do have with each? i am always looking for new tricks.....

[George Miller]

Fine thread is not a good idea with cast iron. You should use a coarse thread.

[Mitch]

If your using the armored cable hold down clamp make sure you drain the cooling system before removing the head nut.. I do remember a long ago post of where the guy was able to remove his dist without loosening the nut..

[tbirdtbird]

Chief,
the metric size u want is 10mm x 1.0 mm
pitch is almost an exact match to 3/8-24
the first 3 threads will be the same, just cut deeper, the last 3 threads will be a new cut, (the hole is not very deep), and you'll be surprised at how well this works.
I may have even left the manifolds on, can't recall. Just go slow, and back out every half turn as with any tap you use

Stuff a rag in the dizzy hole, when done tapping, let'er rip with the blow tip, then remove rag

The dizzy really isn't going anywhere, i don't understand why people jack the hell out of the jam nut, snug is all that is needed

[Mitch]

Can't we just use a stock sized heli coil and then the dist hold down will screw right in?

[BNCHIEF]

Mitch I was thinking about the tang at the end of the heli-coil being a problem A thread sert does not have that heli-coil is fine for a blind hole.

[tbirdtbird]

yep, if head is off. I think it would be tricky with head on, because of the drilling required. No drilling going to 10 mm. I may be wrong

[Big hammer]

Grease on the drill bit and tap will hold most of the chips. I would have to remove the ottwell heater manifold, it's a flat top heater :-(

[BNCHIEF]

I am not worried about chip i will be able to make sure that is not an issue.

[Tom Wesenberg]

not sure how that is different from a helicoil....what comparison do have with each? i am always looking for new tricks.....

Sounds like one is a solid threaded sleeve.

[tbirdtbird]

agree, wondering if there is an advantage one way or the other

[BNCHIEF]

exactly Tom my link will explain it, just thought this might be better, Tbird I like your suggestion as well a lot will pull the manifolds to do the job not a big deal at all. Just appreciate the intelligent thoughtful input from you guys.

[BNCHIEF]

Tbird the thread sert has no tang to break,plus it is used with a thread setting compound it is a threaded bushing so a little different than a heli-coil.

[Mitch]

Once the coil is installed my small jewelers needle nose would grab the tang, they twist right off

Or just block the inside of the hole for the dist shaft and knock the tab off with a little screw rodgerthen retrieve it

[BNCHIEF]

And that would work as well Mitch grease and all which I have done before and I have heli-coiled before as well so this is not new to me the tang was my real concern.

[DaWizard]

When I am making a hole that I don't want to contaminate the area with chips, I simply place a magnet around the drill, or at the hole and let IT do the de-chipping. Blowing it out most often gets chips where you really don't want them, specially in the dizzy hold down screw. If you are drilling that out it will drop chips down past the head gasket hole and we know what is down there.

MY 2¢

[Mitch]

grease on the bit also helps,,, my 4 cents

[BNCHIEF]

Correct Wiz but i will plug every hole that is open if their is a chance there could be a problem I'm your man or so it seems.

[tbirdtbird]

if you are gonna pull the manifolds then you can do a helicoil, you'll have room to drill.
After you drill and tap the hole for the proper helicoil or timesert size, (of course with a rag down the dizzy hole), then blow the chips, remove rag, insert a broom handle or other pipe or metal the same diam. as the dizzy hole to act as a stop for the helicoil or timesert, and let'er rip.
A hemostat will snap off the tang nicely, and you can get those at hardware stores now

[BNCHIEF]

I will pull the manifolds because i can't get get a straight shot at it, time i got to do it right.

[Tom Wesenberg]

I used heli-coils to repair the spark plug threads in the aluminum heads on my BMW R-60, and they work fine. The mirror on the same bike screws into the aluminum clutch handle housing, and it was stripped. I repaired it with a Permatex product where you dip the threaded part (mirror post) in a wax, then mix the solution and put it in the hole, then inset the mirror stem. It held up fine.

You can also use a shop vac on top of the hole to suck up the grit as you drill and tap.

[Mitch]

We use spark plug inserts in aluminum heads all the time cause they come in blown out.
But it's a special insert we use for that in the shop

[BNCHIEF]

I also thought about the vac as well Tom I have a mini-vac. I have also used the set up compound fix as well Tom.

[BNCHIEF]

Thanks for all the input I thought the thread-sert might be a little better repair in the place it is going in. of course length can be an issue with it not sure if you can get different lengths, T-birds idea on the metric bolt would work quite nicely but I would like to make it stock, however this is a "B" police head on this car. The previous owner had the B milled off of this head and he also put some kind of epoxy paint on this engine was real pretty but would not let it dissipate heat block was all pitted around 2-3 valve seats. I could not get the head off so I let my engine builder do it He was the one who told me the head was a B and showed me why and the differences. The engine was also balanced and someone forgot to adjust up the clutch fingers as well.

[Mitch]

Tom here is what we use for spark plugs. It's a product called Perma Plug.. There is no tab to break off and the insert has it's own built in tapered seat for the plug to seal against. Many times the seat is screwed when the plug blows out or when you go to tap it...The tool is a combo tap and installer, once the insert is in place the other tool makes the seat.
We loctite these in as well

[tbirdtbird]

Is that for the modern Ford heads that only have 4 threads per plug.......

[Mitch]

No
It works for any plug, they come in different sizes

[tbirdtbird]

"I repaired it with a Permatex product where you dip the threaded part (mirror post) in a wax, then mix the solution and put it in the hole, then inset the mirror stem. It held up fine."

Tom, I would love to know a PN for this product, it is something I could have used quite a few times over the years, Dave

[Tom Wesenberg]

"I repaired it with a Permatex product where you dip the threaded part (mirror post) in a wax, then mix the solution and put it in the hole, then inset the mirror stem. It held up fine."

Tom, I would love to know a PN for this product, it is something I could have used quite a few times over the years, Dave

That was back in the mid 80's, so I don't know the number, but would ask the auto parts stores.
The wax was just to keep the repair from sticking to the threads while it set up.
Maybe a Google search for "Permatex Thread Repair" would turn up something.

[BNCHIEF]

T bird it was a permatex product if you do not come up with something let me know.

[Bob C]

Loctite has a thread repair also. https://www.grainger.com/ec/pdf/Loct...Data-Sheet.pdf

Bob

[BNCHIEF]

It could have been what bob posted been a long time but the description sounds the same.

[Tom Wesenberg]

Thanks Bob for mentioning Loctite, as it might have been that product. It was just over 30 years ago, so now I'm not sure which brand it was. I couldn't open the pdf, but will see if I can find it using Google.

[Mitch]

I never used this product before

This is what Bob posted

[tbirdtbird]

Well, I've been around the block a few times but this thread repair epoxy is news to me, and will hold up to 128 ft-lbs of torque.
Turns out Permatex has their own brand, which I just ordered,

https://www.amazon.com/Permatex-81668-Stripped-Thread-Repair/dp/B000AL4WAS/ref=pd_sbs_200_2?_encoding=UTF8&psc=1&refRID=67FSDJ32K7HQZ05KR2G8&dpID=51wzX0Xz8tL&preST=_SY300_QL70_&dpSrc=detail

This has been a GREAT thread!

[Mitch]

Technician in a tube lol

[Tom Wesenberg]

Well, I've been around the block a few times but this thread repair epoxy is news to me, and will hold up to 128 ft-lbs of torque.
Turns out Permatex has their own brand, which I just ordered,

https://www.amazon.com/Permatex-81668-Stripped-Thread-Repair/dp/B000AL4WAS/ref=pd_sbs_200_2?_encoding=UTF8&psc=1&refRID=67FSDJ32K7HQZ05KR2G8&dpID=51wzX0Xz8tL&preST=_SY300_QL70_&dpSrc=detail

This has been a GREAT thread!

Yep. that's what I used, and the price is still about the same. I let it set up for 24 hours before using the bike.