With a failure like this, you can turn the engine over by hand and still have enough friction for the broken gear to grab and rotate as well. When the engine is turning over at speed though, that friction is overpowered and lost, causing the cam gear to basically “freewheel” on the camshaft.

Spoiler...Moab ended 2 weeks ago....don’t tell him...shhhhhhh

Wuss. I told you it was a timing issue. Friends and co-workers be damned. Wait for the gear, get it running, drive it to Moab and back. Finish the mission.

 Yeah... I’ve been trying to figure out the problem from my armchair ever since he broke down... I’m glad it was timing because nothing else really makes sense.

Layered fiber, phenolic resin. See also trade names like “Micarta”. Tech that was already thirty years old at this point, bizarrely enough.

I had a ‘69 Volvo 164 that was missing some teeth on the timing gear. Took me forever to figure out why it wouldn’t start. Took me longer to get the gear off.

Also, I don’t think my liver can handle that drinking game right now. Lol

 Lol..

This has got to be a performance art project deconstruction of the slow and inexorable decline of white males in middle America. It would be impossibly sad to read this as straightforward automotive journalism. If Lars von Trier was an associate editor at Road and Track.

I must have missed that?

Pop the distributor cap. If the cam slipped, the rotor won’t be aligned with #1 @ TDC anymore.

david, you are my favorite person in the whole world, Bill Caswell is preaching straight truth to you here, listen to him :) The Boom you heard was explosive compression leaving your engine through an open valve instead of producing power

I will almost bet hard earned cash that you have a cam timing issue, whatever caused is is what you need to find out. The symptoms are exactly like the last timing belt I broke on a non interferience engine. The engine would turn over on the starter as fast as it would with no plugs in the holes. No way a headgasket…

It would be more likely that the compression tester leaks and the compression is fine.

I heard cap, rotor, points and condenser. That’s why I said go back over that stuff. Not that it would directly explain loss of compression (which I forgot he said they verified with a tester), but you could draw a line between a slipped points adjustment making detonation, and blowing out a weak cover gasket. So I’d…

Never worked on a Go Devil engine, but just throwing this out there:

Have you verified your compression tester on a known good engine? Did you rotate the engine with a finger over the sparkplug hole to feel for compression? From the video I can’t imagine what would have caused all 4 cylinders to lose compression simultaneously. It’s possible that your compression tester is bad and you…

The lead photo looks exactly like a screenshot from an episode of Roadkill.

Hate to say at this point, but always double check your recent work. You seemingly gave us a red herring with the no comp assessment, that motor seems like it should have compression, at least enough to start anyways. Before the teardown, did you check for spark and make sure the points didn’t close up? Sorry if I…

Are these chain or gear timed? Is it possible the cam jumped a tooth or two and, while it looks okay spinning with the head off, it’s off enough that it won’t run?