O2 bunghole answers!

[Jake Sternberg]

If y'all are looking for a way to mount an oxygen sensor
on your exhaust pipe, i'll tell ya how I do it.

After calling lots of hardware suppliers including
"Austin Nut & Bolt Company" and being unable to find
ANY 18mm 1.5 pitch nuts, i realized "duh" and walked
down the street to "Austin Cycle Salvage" and dug through
a nut/bolt bin for about 43 seconds and grabbed a handful
of said nuts, which among other things are used for the
rear axle nut on yamaha's and other bikes.  I grabbed four
for my motorcycle project and another few for other stuff.
Total cost was $1.00 plus 7 cents tax.

The only one i've installed so far was into my schoolbus;
I took my oxyacetylene cutting torch (lazy mans' drill)
and burned an appropriate sized hole in the pipe, screwed
a dead oxy sensor into the nut and gripped it with 
vise-grips, and grabbed the MIG welder, oh yeah.. wire feed
for the lazy mechanic.  No inert gas, it uses flux-core wire.

It worked beautifully, just as you would want an oxy sensor
bunghole to turn out, with the sensor held just so in the
exhaust stream.  The only bug with the installation was when
i foolishly removed the dead oxy sensor while mig welding and
then touched the welding wire to the threads of the nut!
Ouch.. Fonked up two oxy sensors trying to figure out what
had happened, thinking the nut had warped.  Then i went at
the tiny blob of weld with a Dremel grinder and once again
sensors would thread in and out like a well-oiled spark plug.

My opinion on brazing a bung on:  It should work, no problem.
I could be wrong, but i intend to do it on my motorcycle so
we'll see.. i'm mounting those sensors about 3.5" from the
exhaust valves.

good luck,
-jake