I just reviewed the thread we did back in May on current style DG's and AI's and venturis. But I need more info on suction regulators. Anyway, I am currently running a new SigmaTek AI (no DG) off of a single 4" venturi. Now I want to install a new SigmaTek DG (given as a present). I assume I will need to install the 9" super venturi as offered by Aircraft Spruce to get enough vacuum for both instruments. Aircraft Spruce says that these super venturis "must" be used with a suction regulator. OK, so I looked at the Airborne Suction regulators in the latest catalog and they now sell for $600. Last year in the Spruce catalog they were $230. What's up with that? Wanna make bets that the price increase may be due to law suits against Parker Hannifin, parent company to Airborne?
I refuse to be extorted for the sum of $600 for a goofy little regulator so let's see what elso we can do. Gahorn, I see you made post about the old "Garwin" style regulators back in May. Were these provided by Cessna as original equipment? What do they look like? Currently I have what looks like a manifold of sorts with a large brass screw in the middle mounted under the glove box. There are 4 3/8" AN fittings screwed into it; one goes to the venturi; one goes to the vacuum guage; one goes to the new AI and the other is capped off. Is this thing possibly the Garwin style? I haven't yet removed it from the glove box to closely examine it. There are I believe 4 mounting screws which attach it to the glove box. When in normal cruise my vacuum guage shows I am pulling about 5-6" of vacuum and the guage needle hops and vibrates very erraticaly. (pulling 5+inches of vaccum with a single 4" venturi at 100 mph? is this right?)
It sounds as if you have a manifold such as the old style that was designed for T&B's only. I think you can do much better with buying a regulator from a salvage yard. You might also contact the association Historian, as I believe he has several extra NOS he might be willing to part with.
5" of Hg is excellent vacuum. Even the new style gyros only need 4.5-5.25". The IFR certified airplanes had two venturies in parallel rather than one in order to have sufficient vacuum to operate two gyros. (VG and DG simultaneously.)
Wanna make bets that the price increase may be due to law suits against Parker Hannifin, parent company to Airborne?