Vacuum

[Gerald_Glaser]

Has anyone run across a cost effective source of vacuum for C145-2 170's ??
I don't want to remove my old venturi, but I do want to spin up the DG and AH before I start rolling... I was hoping that there might be simplpe electric vacuum pump available.

Also, I run consistently with the vacuum guage reading under 4psi... Do I need a second Venturi (The DG runs solidly and never needs reseting once I reach begin my climb.)

Thanks,
Gerry

[GAHorn]

The IFR airplane had 2 venturi's in parallel. See the IPC.
During a 80 mph climb I get 4.0 inches, at 5K feet, I get 6 inches and at 10K I get 4.5 inches, during cruise.
The old AN style gyros only need 3.5 inches. The newer style needs 4.5. I have thought that a simple manual valve, such as a brass fuel valve available from WagAero, Univari, Spruce, etc. and such as those used on Cubs and Aeroncas, should work off of engine intake manifold vacuum on taxi, then switch before takeoff to venturi's. But it's only a thought. I've never tried it.

[Gerald_Glaser]

Gary
In a club I belong to the guys were going to install a vacuum backup off the manifold.

I thought about that option for starting the spinning... I assume it is legal to do. I wondered what the issues might be.

Thanks for the idea. - gg

[GAHorn]

I'm sure a field approval would be required, and placards requiring the switch to venturis before flight.