Get a deep socket and just turn the diameter down on a lathe , for spark plugs there is not a lot of torque so you can turn it down a lot and the socket will not split

i have turned many sockets on the lathe.
just make sure you have a good, rigid turning tool with a carbide cutting insert.
unless the socket is incredibly soft, they will be hard to cut using a tool made of high speed steel.
also, some sockets made of "chineseium" will be VERY hard to turn, due to their unknown material composition.
some of those are so hard the only way to turn them without tool breakage is to use a tool post grinder.

I have seen thin wall lug nut sockets in 13/16ths but they usually have a plastic sleeve that need to be removed to truly make it thinner.
What about a crowsfoot through the hole?

I just bought that expensive socket, going to try it today. I'll let you know if it was worth it.

If I can get plug out without removing header then it's worth it to me...

Ok it's not as easy as the other cylinders but it works! No pulling header to remove the plug!

I will next year pull the header to dimple it anyway to better protect the plug boot but this socket works for me...

The thread title didn't answer that question? No, it won't fit. Hence the request for a thin-wall...

I'm surprised this thread is still going! Good to know the high-dollar sockets will do the job.
No, I don't have a lathe. Another one of those "someday" purchases.

My aluminum heads that are going on this winter take a 5/8" hex plug. I should be able to get a standard 5/8" plug socket in through the fender hole and clear the tube (just) so I won't need 13/16" plugs any more

You proceeded to talk about thin wall impact sockets, which made it unclear, to me anyway, if you had tried a regular one.

Apparently it's unclear only to you. Nobody else felt the need to argue semantics.
It's pretty obvious that this sentence:



meant that the results of my Google searches come up with impact sockets even though that's not what I'm looking for, and that those impact sockets are the same OD as the socket I've got, i.e. too big. At least give me credit for knowing that impact sockets are thicker-walled than regular sockets.

But thanks for continuing the argument, at least it's a thread bump