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Hi Don,

Sounds like you are still missing one of the key elements of the system.

1. You need (and in this case you have) a venturi to make suction when you
are moving.

2. You need (and in this case you have) a proper line to get that suction
from the venturi to the desired instrument with no leaks.

3. You need (and in this case you have) an instrument that can use the
suction to turn the gyro.

4. You need (and this is where you may have the first problem) a path
through the instrument for air to flow from the cabin to the venturi
allowing this flow to turn the gyro. I think you have left this hole
plugged on the instrument and are not allowing flow, you should try to
remove the other instrument plug and it should work.

5. You need (and you do not have) a filter to keep dust and dirt out of
the
gyro so that it will last more than a few hours. There are simple ones
that
look a little like a mushroom that screw into the fitting that is plugged
now on the instrument that will do the job that you need done. On larger
systems they use a central filter and plumb the incoming air to all of the
vacuum driven instruments and some times use vacuum regulators to have the
right vacuum for each instrument.

Hope this helps.

Best regards,
Vern




O.K. I admit it, on some topics I am in the  dark.  In my quest to take my
G model back to original, I installed a  vacuum turn and bank and a 2"
venturi tube where the old 9" used to be.  It  is an overhauled unit, but
I can't get it to work.  Maybe I am  overlooking something.

I left the plug in the hole on the outside of  the venturi.  I am using
the
feed from the hole on the side which mounts to  the fuselage.
I have a 90 degree Neoprene fitting and 1/4" tubing  to the T&B where I
used another 90 degree fitting.  There is no  regulator.
I plumbed the tubing into the hole in the middle of  the T&B and left a
plug in the other hole.

Should I pull the unit and send it back, or is  there some easy way to
test
it?

Don Abbott
N94411







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