VAC reg

[n170bk]

This is the vacuum regulator that came with the Aircraft when I bought it. Does anyone have any information on it? Thanks.

[Bruce Fenstermacher]

What do you want to know about it?

[n170bk]

Make and model, illustrated parts breakdown, instruction on installation and operational adjustments and any additional info that may be helpful to increase more vac on the dual venturi system to run the modern AH and DG. I can only get 1.9 - 2,5 at cruise. It came with small tubing all plumed wrong. I have not seen this reg before. Any help is appreciated. Thanks Bob

[n2582d]

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Made by Eclipse Aviation. Part Number C-51063. Used on Piper Comanche and Aztec. Google the p/n to find numerous used ones for sale. Screw in to increase suction, out to decrease. Air Corps Library has an instruction sheet for sale. Here’s the first of two pages:

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The Aztec service manual doesn’t address maintaining the valve. The original suction lines on the C-170 were 3/8”. You’re asking a lot of the venturis using 1/4” lines with sharp 90° elbows. I’d suggest using Airborne or Rapco vacuum pump fittings where possible. You can find how Cessna originally plumbed the vacuum system with a single venturi here, and dual venturis here. Cleo Bickford wrote a good article in the 2006 fourth quarter edition of The 170 News about how to improve the vacuum system.

[n170bk]

Thank you Gary for your response. I am aware of the limiting vac due to the installation and am in the process of correcting it. I have not seen this reg before.

Thanks to you Bruce as well.

[GAHorn]

YOu’ve mentioned it is plumbed “wrong”….and of course that’s the first thing to correct. It’s not evident from the pic…but that tubing looks small and restrictive.

You might try removing the regulator completely and see what vacuum your venturiis can produce at cruise, and report back.

Also, remember that if your gyro inlet filters are dirty they will never see the proper volume of air regardless of vacuum.

(Keep in mind that the regulator should be in parallel so as to act as a “relief” valve if vacuum should get too high….very unlikely with venturiis.

(I have dual venturiis mounted as depicted in the 170B illustration, but am running Two AN gyros in addition to a modern 3-1/8” pictorial AH and see 4.5” at cruise. However I have the system plumbed with the gyros vacuum being supplied from/thru a manifold, and the reg is connected directly to that manifold (see it connected to the manifold via a black hose)

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