Header bolts-tool suggestions?

[Flatcap]

This truck has been blowing from the headers since I bought it about 6 weeks ago so I quickly ordered a fresh gasket set to try solve the problem. Parts came so I decided to start the job after coming back from a drive. I cannot believe that the bolts are only 10mm and virtually impossible to get a socket on to remove them due to how damn close they are to the tubes! Have any of you guys come across this before and what did you use to get them removed? I now know why they are leaking and that's because the previous owner couldn't get in to torque them down properly.
Some of the offending bolts:

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[HotWheelsBurban]

You may have to use an open end wrench to get the bolts out. They may also be 3/8" head as that is pretty close to 10mm. Working on GM stuff you learn the metric and inch fractional comparison quickly. Once you've got the header bolts out, you may be able to dimple the tubes close to the bolt locations. I've seen some headers that have that done already. Good luck!

 

[PlayingWithTBI]

My son brought his 1/4" drive set of swivel sockets which fit on mine OK but, my tubes may be smaller than yours.

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[618 Syndicate]

Dent the headers. No appreciable drop in performance with much easier access.

 

[Supercharged111]

The headers on my truck are pinched by the bolts which improves access and ditto on the 3/8 comment above.

 

[sntrym]

Defintely 3/8". Get yourself a long handled combination wrench. It will make the job much easier. So may heating them up.

 

[Flatcap]

Thanks guys for the info. I will keep you posted on what happens!

 

[kennythewelder]

I have tried just about every trick in the book. I have had my headers on my truck for a long time. 7 or 8 years, maybe longer, IDK. I find that felpro header gaskets work best. They have to be header gaskets, not exhaust manifold gaskets. As for bolts dido, I have tried about everything out there. An open end, box end wrench of good quality with a cheater pipe about 18 inches long for me, has worked best. I use a torque wrench on the bolts that I can get to, and the box end with the cheater pipe where I can not get a socket on the bolt. The current gaskets have been on my truck for several years, 4, or 5 years with no leaks. Also it helps to retorque your bolts at about 50 miles or so. After you run the truck some, and the bolts heat, expand and contract a few times. Only 1 retorque is needed most of the time.

 

[delta_p]

deleted

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[TechNova]

I have a Snap On wrench I bought over 30 years ago for headers. Both ends are open but they are at two different angles, one end being almost 90 degrees