I like the undercowl venturi so much I am thinking of forgetting the vacuum

pump.
Turn it off when flying VFR. Less HP loss and less weight. I don't believe
in an HSI or a directional gyros anyway with today's solid state/vertical
cardcompasses and GPS heading. <<<<

I agree that the HI is a complete waste of money, other than the fact that you cant fly legal IFR without one (the FAA will realize this in about, oh, 30 years).  One thing to remember about the under cowl system, however, is that is is not good for the gyro to be flown while not running.  It can create flat spots in the bearings.

Dave Leonard

Good question Dave.
I have heard that said but I wonder what level of vibration was assumed.
If I shock mount it and I use a smooth rotary engine does that still apply?
Obviously if it sits around on the shelf for five years that does not
hurt the bearings. Maybe we need to contact the manufacture and ask them
what level of vibration and frequency damages the bearings. 

Paul Lamar
 
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