I once had a 13mm bolt that was in a place too tight to turn a wrench.

I took a 13mm combination wrench and sawed it in half with a hacksaw. 
With this shorter wrench, I was able to get the box end on the bolt
and turn it little by little.  Maybe that will work for you?

On 6/12/05, Mike Jeffrey <oldbus@gmail.com> wrote:
> Hello! and happy Sunday,
> 
> I'm looking for tool advice... there's a bolt on the exhaust system of
> my '83 CA aircooled that's particularly tricky to get at. It's the top
> bolt (originally a stud) at the junction of the right-side heat
> exchanger and the cross pipe. All of the tin is installed around it,
> so access is very tight - I can't turn it with a wrench, and my
> ratchet is too bulky.
> 
> Can anyone recommend a tool that fits in there well enough to turn the
> bolt? Some strange ratchet, a 90 degree bend, etc...? It seems that
> there's enough space for the socket in there, but not much more than
> that.
> 
> Thanks so much! Any help much appreciated.
> Mike.
>