Can we talk about JB Weld?
 

I've never used the stuff, it always kind of had a bad inference for me because of a certain unscrupulous Porsche engine builder that we used to discuss here. :)

It's actually metal epoxy, right? Pretty strong and permanent? Can it be filed or dremeled after it sets? I need to repair a carburetor that is otherwise going to be disposed of and it would be a huge waste. It's not something that would experience any real type of stress once it's fixed, (just air passing through), but it absolutely cannot chunk loose or fail, either.

What say ye?

I now a lot of folks that swear by the stuff. It is pretty amazing. I would try it before trashing a carb.

that stuff saved me. no it actually saved a buddy i was caravaning with. his 928, he had a water fitting that popped out at ButtonWillow.

Jack Olsen actually gave me some JB-Weld..we used it and that fitting is still on there!! i was super skeptical and was telling my buddy to call a tow truck already. but it felt like success the second we plunged that fitting back in.

it'c certainly worth the hail-mary on that carb.

Jb weld or metal putty should fix it right up.
If you’re uncomfortable than you can always solder it if it’s just a air passage. Make sure you preheat the surrounding metal before soldering the hole. Make sure it’s disassembled so you don’t damage any rubber seals or gaskets.
Good luck
Tony

Thanks, all! Is metal putty something that cures to a hard surface or stays pliable?

As I recall they have some formulas specifically for fuel/tank repair.

A-B types (mix) or the sticks that you knead get hard. I've machined it (filled holes and drilled)

I think you want seal-all for this.

surface prep is everything.

Shaun is correct. Make certain there is some mechanical roughness for the patch to bite to.

If it sticks, it will be fine.

It doesn't get rock hard. You can bend it. There was a thread a while ago where a guy in france built up a huge blob of JB on his engine case where the right cam oil line fitting broke the case. I wonder how that worked out over time.

In 2010 we did an engine rebuild on my RX7. I wanted to go with a very aggressive port job on the intake ports to open them up as much as possible. Rotary engines perform sort of like a 2 stroke engine. Air/Fuel gets pulled in a side port, squeezed, ignited and send out the exhaust in 1 rotation x 3 faces of a rotor x 2 (or 3 in some cases) rotors.

The port job we planned on using would compromise the water jacket that ran near it. That meant we needed to seal back up the water jacket then clean up the repair.

I flat out refused to believe JB weld was the solution. I purchased 2-3 other kinds of epoxies in an effort to find the perfect one, we used them on test pieces, boiled them in water, exposed them to oil and gas and put them through hell. Every one failed.

I contacted 2 very well known engine builders, both said they use JB weld. So we conceded to used it.

10 years later and I would guess 30K miles on that engine now and it still runs strong with no sign of the JB weld failing.

this and surgically clean. I used acetone.

That’s an amazing story and it’s hard to argue w verified results. I’m sold and going to use it, I’ll post the results. My only concern is how well it can be *dremeled*, I want to match the original surface as closely as possible.

It sands pretty well. use a pneumatic dremel pen and diamond bit for detail and hard to reach places.

Astro Pneumatic Tool 218 1/8" Pencil Type Die Grinder - 56,000RPM

http://forums.pelicanparts.com/uploa...1592846745.jpg

All I have is a standard Dremel tool, hope it fits in the passage, come to think of it.

That pneumatic pen is amazing, you can use it with precision that an electric Dremel would never dream of. It's a scalpel compared to a Dremel ax.

And it is not expensive, I am going to order one.

I used it once back in the day to fill a deeply scratched cylinder on a 250ci chevy 6 in a 1967 van. Short story is the van was smoking, using coolant running on 4 cyls basically. I tore it apart and at some point the head gasket blew between 3/4 and actually grooved the block from the steam / cylinder pressure going back and forth. Also upon closer inspection saw #4 cylinder gouged vertically from a broken ring. Guy didn't have enough money to replace the short block/ engine used or otherwise.

So I removed the pan, removed #4 piston/ rod. Bought 1 new piston- ring set. I cleaned the surface of the block and the cylinder wall, filled in with JB. let it sit for @2 days. I carefully sanded the deck until smooth, checked it with a carpenter's straightedge. I honed #4 until it looked good, put in the new piston/ ring set used Fel-pro gaskets - believe it or not it lasted quite a long time.

I don't see a CFM spec. Do you think I can I run that off a small jobsite compressor (occasionally, short duty cycle)

Absolutely. It's tiny so while it runs through a lot of air, it's a tiny little thing so I don't expect it would be a problem. Since it has no torque, it does need to run at high speed for any kind of cutting with dremel discs.

It's amazing stuff - I use it in manufacturing production equipment. I have also used it repair the riveted part on my ash tray that goes in my 944.

Added to cart. Thanks Shaun!

try devcon that stuff is amazing

I have two of those - probably my most used tool, and it requires very little air to run, even at max (I use it mainly with a 60 gallon, 4.5hp compressor and the thing barely needs to run if only the pencil grinder is being used). I've also used it with a tiny compressor, and no issue.

Another epoxy that I HIGHLY recommend is Loctite's Hysol E-40HT. High temp, oil and gas resistant, truly structural. I called Loctite after buying a new steering rack for my 01 Tundra. The hydraulic threaded female on the rack was stripped out. Inside the box was a letter from the remanufacturer telling you to be careful, the threads easily strip and they won't take it back if they are. Of course someone did strip them and then returned it to Autozone and they sold it to me. Instead of trying to return it, I called Loctite and that's what they recommended. That was 4 years ago and rack is doing just fine. I use it on 928 intake cracks (cast magnesium) and never had a call back. Have used it in other situations, it's a true structural epoxy.

All epoxies can be removed by heat. I don't agree with JWW's statement that it stays somewhat flexible but the term is subjective.

Yes, there are other products that mimic JB and most, if not all contain metal shavings as part of the 2-part composite. Original JB takes at LEAST overnight to get hard enough to machine. You can subject the part to low heat after the initial cure period, 2-3 hours at room temp. Locktite brought out a fast metal epoxy repair and then JB brought out theirs, in that order IIRC.

Then there's soldering on cast metal parts such as a carburetor body with zinc. An oversold product in that class is Muggy Weld. I buy my stuff at the LWS and it's not cheap.

https://i.ebayimg.com/images/g/elEAA...e21/s-l640.jpg

Look at the 5th item in the list. It's tricky to use but you can actually do it with a good propane bottle torch with a pencil flame. MAPP gas is better but they don't sell that siht anymore. There are substitutes that burn slightly hotter than propane, like 130º hotter and that doesn't make much difference, so stick with propane. It's much cheaper.

Here's a video about the stuff. Nevermind that he destroyed the seal of the Welch plug at the end of the bore. I guess he now can solder that up.

Zeke, I've had success with Blue Demon aluminium brazing rods https://www.globalweldingsupplies.co.nz/product-page.php?sku=WDABD32 the trick was to get the aluminum very hot, but well short of melting, with a Map-pro torch then lightly dragging the alloy rod over it.

I did lots of testing on scrap aluminum.

Thanks, I’ll pick one up. I don’t have a compressor here but I have one at home in CA. I’m thinking now that I’ll just repair it w a hand file, really carefully. Here is what I picked up today and the damage:

http://forums.pelicanparts.com/uploa...1592862355.jpg
http://forums.pelicanparts.com/uploa...1592862355.jpg
http://forums.pelicanparts.com/uploa...1592862843.jpg

Marine-Tex is kind of a wonder epoxy similar to JB Weld.

Not sure of its availability in inland areas, but... I've used it (and JB) for some crafty fixes, that saved me time and money..

Marine-Tex

Those pretty pictures put my “git ‘er done!” work to shame. I still like seeing them.
I worked with small pneumatic peens, repairing aluminum castings, when I was in college. Great little tools.

If you have lakes there are boat places that sell it. I have used Marine-Tex several times.

Marine Tex = JB Weld X 10..........Both are good.....

How so? I don’t need it to have Herculean strength, just bond well and be file-able. Also able to handle a small amount of fuel passing by it.

I cure JB weld in the oven at low heat overnight.
It cures rock hard.

Without heat, it cures kinda flexy and softer.

JB Weld. Don't leave home without it.

Devcon 10760 is for the adults in the room Expensive but when it has to work It does

Maybe you should be more specific, since Wayne recommended it in his rebuild book.

JB Weld? For what situation(s)? :confused:

I would not rate Marine Tex ten times a good as JB. Maybe he means +10

Traditional JB Weld had 5020 psi of tensile strength. Marine-Tex, 4,000 psi.

There may be other factors that are better one vs the other but they are in the same ball park.

JB Weld
There are several spots on the case where an original bonding/sealing agent was placed. These are the places where a factory dowel pin or plug has been inserted into the case. JB Weld is an excellent heavy-duty epoxy that can be used to replace the dabs of factory epoxy that help seal some of these areas of the case and chain housings.

https://www.pelicanparts.com/cgi-bin/wizards/Parts_Wizard.cgi?command=step3&wizard_root=911_eng ine_rebuild