Epoxy that is like JB Weld x 1000
 

As the title says, I am looking for a two part epoxy system that I can put on some threads of a stud, and then screw it into, say, threads that are one size bigger, and then walk away for 24 hours. On my return it needs to create a watertight seal and withstand me torquing it to say 70 ft lbs.
What is there that can do this?
Thanks in advance and Merry Christmas you little jerks!

Yeah, unless it's just totally inaccessible, this sounds like a threaded insert job to me.

70 ft lbs is a non-trivial amount of torque, and I assume that vibration and heat-cycling will also be involved.

I spec'd out an epoxy like this at work once. They make it. It's used it for satellites or something. I think it was about $1500 a gallon. I decided to use rivets instead.

Here's what happened.
1948 Willys flathead 4 cylinder. Was running like it had a vacuum leak, and the exhaust manifold had a nasty crack in it. I removed it all, and broke off the stud that's closest to the firewall (and has the least amount of room to get to) flush with the block. I managed to drill out the old stud, which consisted of drilling it completely out. No heat/ ez out would have it to budge. I ran a 3/8-16 tap through it to clean the threads up, which looked fine. Thread the new stud in it, and it feels sloppy. When I say sloppy, I mean it wiggles a little bit, and when you try to torque it, it feels like it's pulling out. This stud also blocks off a water jacket, so it must be tight and sealed. Here's photos with a right angle die grinder to show lack of clearance, and then the photo with the stud screwed in.
https://cimg8.ibsrv.net/gimg/www.mia...563d18272c.jpg
https://cimg0.ibsrv.net/gimg/www.mia...a4f1897cb6.png

I'd tap it bigger.

Don't have any tap sockets? To use with a ratchet? Would fit in there easy.

Best solution would be to drill/tap it out to the next size up.

But given that the stud still threads in, I wonder if JB weld would work. It would probably boil down to how much a new head costs if something goes wrong.

Head? It's a flathead...so that option isn't there. I wonder if a helicoil on the threads would simply tighten up the slop?

I seriously would want to do it right if it were my truck. That means drilling, tapping, and putting in an insert. Even if I had a vial of wackbards' $1,500 spacecraft epoxy, I wouldn't use it on an exhaust stud.

It's such a bitch to drill in that tight spot. I almost have to pull the tub or pull the motor.

Oh man, you got plenty of room if you can get a right angle grinder in there. My recommendation is to
​​​get a cheap dotco right angle pneumatic drill motor. They are super low profile. The cutters thread into the head instead of using a chuck. Get the drill motor, the correct diameter cutter, and the correct size drill bushing. It's hard to drill straight with one of these drill motors. You might have to get two cutters of different lengths, cut the first part of the hole with a really short cutter, and then when you have to use the longer cutter, just put the cutter and bushing on the hole before threading the cutter on to the drill motor. The threading is really short, like less than a half inch.

**EDIT** ok, maybe building planes has skewed my perspective on affordable. Those motors are expensive from dotco.

Here's one used on eBay for $140

https://m.ebay.com/itm/Dotco-90-degr...-/302576639395

I think this style has a 1" head

I thought this was just a hilarious Joe Perez post until I scrolled up.