Same deal on Chrysler 3.0s (Mitsubishi 6G72).

I’ve saved a few people at shops by informing them of that tidbit

They increase the effective volume of the combustion chamber, reducing compression.

it depends.

That’s not what valve reliefs are for. They’re to raise compression and to ensure that the piston doesn’t smash into the valves while the engine is timed properly.

Would there be a reason not to do this? Other than added cost of machining it seems like a pretty desirable feature to make someone’s engine not get fucked up.

So I learned that Knight engines were sleeve-valve engines for cars.

I’m surprised you didn’t mention “eyebrows” that are sometimes machined into pistons to prevent contact if the timing belt fails.

Of course, with a sleeve valve engine, none of these problems with pesky belt changing are an irrelevance.

Fun fact. The 2.0L Zeneca motor in the 00-04 focus is a non-interference engine. UNLESS you shave .040" from the head to raise the compression to 10.8:1 and add high lift cams. Then it becomes an interference motor. Ask me how I know.....

Both Honda and Mitsubishi have moved to chains, although I know that the 4B11T in the Evo X have chain stretch problems and the K20 and K24 have timing chain tensioner failures which can still lead to interference problems. Maintenance is still necessary, chains aren’t lifelong solutions.

Volkswagen is bad enough at chains that you want a belt with their interference engines.

A lot of tears and needing to find a new way home?

There have been lots of problems with chain guides. They break, shear, come loose and let too much slack into the timing chain that it skips and kaboom. Happened to my bud on two 4.0 V6 Ford engines in a row within 3 days.

Timing chains can ‘stretch’.. more like wear between all the parts cause minor play and the chain can skip a link and through timing off. Or I may be wrong on my exact understanding.

Depending on the cost of labor to pull the head, machine it straight, install new valves and button everything back up again, sometimes swapping in a used engine is a much better bet. There’s also the possibility that the pistons will be too damaged and will have to replaced as well.

Some cars have known issues with timing chains and should be addressed accordingly. By and large, though, timing chains shouldn’t ever need to be touched.

The casual nature of the workers standing around capturing video of the crash and its aftermath is hilarious,

Man, those shipping companies are going to get flooded with inquiries. But, I don’t think their business is sunk yet, though it did take a hit.