This Guy Created A Working Lawnmower Engine Head Out Of Nothing But Epoxy

Engineers tend to ask the kinds of questions nobody else has ever even dreamed of asking. I've never even remotely considered asking whether or not it would be possible to build a functional cylinder head from J-B Weld two-part cold weld epoxy. Maybe that's why I'm not an engineer. In any case, a few years back the same maniacal genius behind Project Farm on YouTube who brought us tests on which jack stands can kill you, decided to answer that question about cylinder heads. Not only to see if an engine would start with a J-B Weld cylinder head, but if it would stay running for over one minute. Let's see how it was done! 

This ridiculous use of the scientific method began by pouring and mixing four entire batch tubes of the epoxy and four matching tubes of hardener, about twenty full fluid ounces of the silver sticky stuff. That giant batch of goop was poured into a form to get it more or less the right shape and let cure for several days in order to be sure it was as robust as it could be. 

With the basics complete, the hardened block was put into a makeshift jig and hit on both sides with a belt sander to make sure it was as flat as could be. Using the original cylinder head as a template for the new one to be machined, the whole shooting match was bopped into a drill press and eight bolt holes were drilled through the new head to properly bolt it to the engine it would be topping. A ninth hole was drilled and tapped in the center for a spark plug to sit in. 

With all the holes drilled, and using the cylinder head gasket as a template for the combustion chamber, a mostly-correct shape was hand-machined into the inner workings. These reliefs in the cylinder head are necessary to make space for the engine's valvetrain to operate. If a cylinder cant' get oxygen in or spent exhaust gasses out, it simply won't run. And with that, the cylinder head is complete and ready to be bolted to the engine for testing. 

You probably already gleaned from the title that Project Farm was able to get the engine to run and stay running for over one minute. Personally, I would have liked to have seen just how long the engine would run before something catastrophic happened, but the test didn't go that far. If I had to guess how it would have failed, I'd say blowing the spark plug threads out and losing ignition. I have no idea how long it would take to create enough heat in the engine to do that, though. Without the stock cylinder head's cooling vanes, I would also wager this thing would get pretty hot pretty quickly. 

There probably aren't too many mechanical lessons to learn from this experiment — it's just fun to watch by my standards — and there are limits to this sort of hacked-together DIY engineering. Running anything larger than a small industrial single cylinder engine with a J-B Weld head seems unlikely, so don't bother trying to replace the head on your car with a sheet of this stuff. But, you know, if you need to repair a small portion of your failing cylinder head with J-B Weld, you can probably trust it to run a little longer now that you've seen this.