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Old April 23rd 17, 06:50 PM posted to rec.aviation.owning
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Default IFR in a vintage 172 - vacuum system

On Sunday, January 22, 2017 at 12:14:32 PM UTC-7, Charlie Gibbs wrote:
Well, at long last I've decided to go for my instrument rating. I'm having
a ball (aside from yesterday's disastrous simulator session), but now I'm
facing the dilemma that every instrument student has to deal with: where to
find an IFR-capable aircraft. My 1961-vintage 172B's panel has a six-pack,
a KY-97A, a GTR-225, and an ancient 300-series ARC ADF. Good solid comms,
but not much else. That's nothing a boatload of money can't fix, except
for one thing: my vacuum gyros are powered by venturis. (It's great fun
when a young hotshot instructor from the flying school next door wanders
over, points to the venturis, and says, "What's that?")

What makes it difficult is that my Continental O-300C (150 SMOH and
purring like a kitten) has no option for a vacuum pump. The O-300D
was the first model that provided a mounting pad on the rear case.

All my buddies walk me through Trade-A-Plane, etc., pointing out nice
Cherokee 180s decked out with a 430W and a KX-155. That's well and
good, but the old girl has been in the family for over 40 years.
Heck, she _is_ family - my wife is doing her PPL in her right now.

So... is there any way to retrofit a vacuum system in my plane?
Adding a heated pitot and alternate static are trivial, and the
radios, as I mentioned above, are just a matter of money. But I
don't think it would be a good idea to take off into the soup when
my gyros aren't spun up until several minutes into the flight.
And conditions that would ice up a carburetor are bound to be
at least as bad for venturis - and they have no equivalent of
carburetor heat.

Common wisdom says get another airplane. But there's the
sentimental factor here. Any ideas?

/~\ lid (Charlie Gibbs)
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Nothing wrong with using the venturi vac system unless you get into ice. BH