Flying T337G with attitude indicator removed

[kevin]

Folks, I received this inquiry via email today, and I don't know the answer, but have posted it in case someone else on the board does. Thanks. -Kevin

Good Afternoon,

A friend of mine has a T337G and he was wondering if it is possible to run the Aircraft Engines with
Attitude Indicator removed. He has it out for Overhaul and wants to run them.
If it is possible to run the engines, should it be done with the lines capped, open, or
with a tube between the pressure and vacuum line. Will it damage the pump?
Will anything else go bad? What about the rear engine vacuum pump?
He is also asking if it can be flown in the pattern with this component removed and
lines open, capped, or connected with the tube. I tell him to wait, but he is all air
when it comes to free time(time off).

Regards,
Chris