How do I remove this nut?
 

I bought a mid time O320 with an old 4 pipe Vetterman system for my RV-4. I want to take the pipes off and have them sandblasted to take some of the corrosion off. My problem is that I have no clue on how to remove this bolt. All the other ones will be difficult to remove but this one looks impossible. I can't get anything in there. It is the exhaust pipe coming out of the number 4 cylinder. Is there a special tool for this?

USE A BENCH GRINDER.......
 

Grab a craftsman open end wrench (or a cheaper one) and start grinding on it till it fits. Don't let the wrench get hot, keep it cool in water as you grind on it. This will be the start of your custom tool collection.

The stud looks longer than it should be, but bring the nut down as far as you can and go to another nut. As the pipes drop down, you will have greater access to get the nut off.

Install a shorter stud.

Looks like you will have to use an open end wrench, maybe even grind one down to be thinner. You will have to bring the nut down until it touches the pipe then work the pipe down away from the head to completely remove the nut. Just remember you will have to do the same when you put the exhaust back on.

In a more direct answer; loosen nut, wiggle header down, loosen nut, wiggle header down... Repeat until the nut is removed.

I would get a box-end wrench and try that. Usually the higher the quality of the wrench, the thinner they are as far as the wall thickness of the socket, or "box".
Grind down the walls of a cheap wrench if you want. Don't forget penetrating oil; spray some on and let it sit overnight.
You won't get an open end wrench in there.

Sometimes a Craftsman...
 

...flex socket with a 1/4 inch drive and an extension will work here.



It depends on the curve of the exhaust pipe, but it's worth a try...

Gil is correct.

Looking at the weld on the flange, I would bet that it is NOT a Vetterman exhaust.

Are you sure it is Stainless Steel exhaust? I have never seen that much corrosion an a Vetterman Stainless Steel exhaust.

Not all are stainless
 

Gary,

In the early days of Vetterman his exhaust was not stainless. Still I do wonder if the one pictured here is a Vetterman.

To be clear....Gil's method will NOT work for this nut as the stud will interfere or bottom out in the socket due it's extended length. It will work (and is what I use) for appropriately sized studs. You'll have to use the ground down wrench method previously mentioned until you have 'less stud' showing.

You're bonna be hard pressed to convince me that this is a Vetterman system.
 

My RV-6 had one of the very early Vetterman mild steel systems. It was constructed MUCH better than this.
This looks to me more like one of the early Alan Tolle systems.
Bring that picture to LOE and let's discuss it with Larry.