This guy created a working lawn mower engine head out of nothing but epoxy – Jalopnik

Engineers tend to ask the kinds of questions that no one else has ever dreamed of. I never even thought to ask whether or not it would be possible to build a functional cylinder head from two-part cold weld epoxy from JB Weld. Maybe that’s why I’m not an engineer. Anyway, a few years ago, the same maniacal genius behind Project Farm on YouTube, who brought us tests that show jack stands can kill you, decided to answer that question about cylinder heads. Not just to see whether an engine would start with a JB Weld cylinder head, but whether it would continue to run for more than a minute. Let’s see how it was done!

This ridiculous use of the scientific method began with pouring and mixing four full batch tubes of epoxy and four matching tubes of hardener, about twenty full fluid ounces of silver goo. That huge batch of junk was poured into a mold to give it more or less the right shape and left to harden for a few days to make sure it was as sturdy as it could be.

Once the base was completed, the hardened block was placed in a makeshift mold and pounded on both sides with a belt sander to ensure it was as flat as possible. Using the original cylinder head as a template for the new one to be machined, the entire shooting match was put into a drill press and eight bolt holes were drilled through the new head to properly attach it to the engine it would be placed on. A ninth hole was drilled and tapped in the center to accommodate a spark plug.

You’ve probably already gathered from the title that Project Farm managed to get the engine running and keep it running for more than a minute. Personally, I would have liked to see 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 blow out the spark plug wires and lose ignition. However, I have no idea how long it would take to create enough heat in the engine to do that. Without the stock cylinder head cooling vanes, I bet this thing would get pretty hot pretty quickly.

There probably aren’t many mechanical lessons to be learned from this experiment (by my standards, it’s just fun to watch) and there are limits to this kind of hacked-together DIY engineering. It seems unlikely to use anything bigger than a small industrial single-cylinder engine with a JB Weld head, so don’t bother replacing your car’s head with a sheet of this stuff. But you know, if you need to repair a small part of your failed cylinder head with JB Weld, you can probably trust it to last a little longer now that you’ve seen this.