JB Weld on Exhaust Manifold ?????

I was reading another older thread on her about someone that used JB Weld on a cracked engine block. They said it worked well on a HOT engine. Someone else said that JB Weld is rated to 600 degrees F.
OK, but will it work on an exhaust manifold? I have one of the 3 studs that refuse to thread into the manifold anymore. The stud is new, so the manifold threads are shot. I am not willing to change the whole manifold since I probably wont keep the car too much longer, and the new stud will probably outlast the car. I thought that JB Weld might keep it in there, and after it dries well, I can tighten the nut, (but not real tight).
I have no clue how hot an exhaust manifold gets????? It it over 600F ???
This is a Chevy 307 engine (the olds engine they used). There is no way to drill thru this manifold and use a nut and bolt (some can do this, but not this one because of the shape).
Thanks for all help
Mark
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snipped-for-privacy@UNLISTED.com wrote:

JB ain't going to handle it my friend. They make an aftermarket clamp that can be used instead of a bolt. You could rethread the hole to a larger size. If you can get a bolt there, you can get a tap there too. As a last ditch effort you can use two of the best quality screw clamps in an X pattern between the pipe flange and manifold. This really works.
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wrote:

Of all the things suggested, and THANKS TO EVERYONE, that clamp sounds like it would probably be the easiest thing to use. Do they sell them at a place like NAPA / CARQUEST / AUTOZONE? Or can I order online (website referals please), or do I need to go to a muffler shop? I should note I live in a rural area and specialty parts are impossible to find locally. We have a Napa and Carquest. If I drive an hour, there's Autozone.
I have TWO of the THREE bolts securely tightened now, so I really just need to pull that 3rd one tight. I used a custom made (at muffler shop), split flange, and it's like 1/4 inch thick. So, drilling oversive would require removal of the whole exxhaust system again, and that does not sound like what I want to do. In reality, it's a 17 year old high milage car, and while a complete new exhaust system including manifold would be the ideal, I just want to get the exhaust quiet again, before the cops pull me over. Actually, Its very quiet now. One pipe, one muffler one donut and the split flange did the trick. But I already know that donut will burn out quickly if I dont get that 3rd bolt tightened.
Mark
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Try a "C" clamp if there is enough room. One of those wound up will hold it and save the gasket.
Roy
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snipped-for-privacy@UNLISTED.com wrote:

nope. a helicoil is what you need. you still will need to drill the hole oversize and then tap the hole with the special tap provided with the helicoil kit.
good luck,
nate
PS- there *was* a Chevy 307 as well; I think it was a 327/350 bore with a 283 stroke, IIRC. My dad had one in his '73 pickup.
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wrote:

The Olds 307 was originally a Chevy engine, which GM later used in most of its car lines. After a class action lawsuit, GM took a lot of heat for installing their "GM product" engines in Oldsmobiles, Pontiacs and Buicks . Seems some people wanted an Olds 307, not a Chevy 307. At one time, each division had unique engines, but that made little sense from an economic view when the industry was getting creamed in the mid 70's. Anyway, it had the 283's bore of 3.875" and the 327's stroke of 3.25". This is not to be confused with the legendary 302 ci motor, which had a 327's 4.00" bore and a 283's 3.00" stroke. Sweet.
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wrote:

altho' they may have shared the same bore & stroke. Completely interchangeable, engine-mount & trans. pattern, with the Olds 350--but not with the Chevy 350, as was the Chevy 307. Where you mentioned 'sweet', you were dead on! That Chevy 302, which was basically what we hot-rodders had done years earlier, was a 283 bored out to 4 inches--or, as you said, a 327 bore & a 283 stroke. Man, was it a screamer--& "sweet"!!!. s
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snipped-for-privacy@UNLISTED.com wrote:

Not going to work.
Can you get a tap in there and tap the hole out to the next oversize, then go with that larger size stud? I've dealt with many a stripped internal thread in this way.
John
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wrote:

Thanks John
THere seems to be one problem though. This hole is not one that goes all the way through. It goes into the casting and is "internal" in the manifold itself. The hole is only maybe 5/8 inch deep. I know taps are tapered, so I will never get it in far enough to make the actual threads. What can I do to solve that?
Mark
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Use a bottoming tap (flat bottom)....not a plug tap<tapered>

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BAD 4 GOOD wrote:

Quite right. I like to start with a tapered tap and then back it out and switch to the bottoming tap as the taper type is easier to start.
John
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snipped-for-privacy@UNLISTED.com wrote:

Buy a "bottoming tap" or if you have a lot of old taps laying around just cut one off after the taper and grind just enough of a chamfer on the end to let it start in the threads, but no more. You will need to start tapping the hole with a regular tap and then finish them up with the bottom tap. I've actually modified a Helicoil tap like this just for this situation (wasn't a manifold though, it was a blind hole into a thermostatic fan clutch that was stripped in my case.)
good luck,
nate
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I'm glad you mentioned cutting off a regular tap. Where I live, there is no place to buy specialty tools like that. In these rural areas one is lucky to be able to get a the brand of spark plug desired.
Mark
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snipped-for-privacy@UNLISTED.com wrote:

I suppose I should have mentioned that you will need an abrasive wheel, like an air cutoff tool - if you try to do it with a hacksaw you will be cursing my name...
nate
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snipped-for-privacy@UNLISTED.com wrote:
I read about someone who used JB Weld on a cracked engine block. They said it worked well on a HOTengine. Someone else said JB Weld is rated to 600 degrees F. OK, but will it work on an exhaust manifold? _____________________________________________
Probably not. One way to break down epoxy bonded joints is to heat them with a torch. Bonds which would work in a hot engine block would probably not survive the temperature in a hotter exhaust manifold.
If possible, the cleanest fix for a stripped thread in the manifold stud boss is to install a helicoil insert.
Another possibility is to tap-drill the blind stud hole all the way through and re-tap the thread though so you can use a regular hex screw or a longer stud.
Another possiblilty (not very elegant) is to drill or grind a hole through the side of the stud boss until the blind stud hole is exposed, then use tightened loops of wire to pull the head pipe flange tight.
Good luck.
Rodan.
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I agree, a tapped repair is best for studs, as for putty to fill voids, I've heard of a product called Pyro Putty supposedly made to withstand tremendous heat, used to fasten motorcycle pipes to cylinder head. Furnace Cement withstands the heat, but is short lived in Auto applications, vibration being cause. Nix to High temperature Silicone too, it cooks away on head pipes can survive aft of cat.
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