MAP sensor location on Jab 3300

[Cess32cw]

Am finally getting to the end of my conversion from a turbo aerovee to a new CAMit3300 with a Bing. Since I have a manifold pressure sender I figured I might as well hook it up on the new engine. Any thoughts on where I should tap into the induction system to obtain the most accurate reading? I am running a HACman and figured I would plumb into it, where it taps in at the carb/air filter but the reading that I am seeing is way high (46 plus inches). Am I better off plumbing into the intake tube at one of the cylinders?

[Sonex1517]

I have no suggestions, but am very interested to hear the results. I just swapped my AeroVee for a Jabiru 3300 Gen 4, am working on a HACman solution, and was thinking along the same lines.

Please post your results. Thanks.

[fastj22]

Am finally getting to the end of my conversion from a turbo aerovee to a new CAMit3300 with a Bing. Since I have a manifold pressure sender I figured I might as well hook it up on the new engine. Any thoughts on where I should tap into the induction system to obtain the most accurate reading? I am running a HACman and figured I would plumb into it, where it taps in at the carb/air filter but the reading that I am seeing is way high (46 plus inches). Am I better off plumbing into the intake tube at one of the cylinders?

I plumbed one directly into the intake manifold on the bottom. Just drilled and tapped a ⅛ NPT hole. Easy peasy.

[sonex892.]

The vacuum fitting is located on the bottom of the carb jst remove the small screw and put the vac hose there

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[Cess32cw]

I thought that was what I did via a "T" fitting as part of the Hacman installation. As I mentioned, I am getting a reading of 46 inches at that location. Is it possible that I would get a different reading at that location as opposed to the intake manifold as John suggests in his post?

[sonex892.]

The hacman actually gets cut into the middle of the mixture balance tube. The balance tube is a small tube that goes between the carb and the clean air side of the carb. The balance tube port is located on the inlet air side of the carb near the fuel inlet.
The vacuum port is under the carb right near the main rubber coupling to the manifold. Its right next to the idle mixture screw.
The vac port when not used is plugged wth a 3 or 4mm screw.

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[DCASonex]

With a tee in that fitting from bottom of carb to the HACman, should be same as direct to the carb, but should be quite easy and informative to tap the manifold for a fitting to test out if results are the same. 46" might be correct ??? or if feeding to an electronic display, scaling might be off, or ??. Some hose fittings are available to fit 1/4-28 tapped holes which would be quicker and less messy for quick test, least likely to disrupt air flow in the manifold, and easy to plug if not needed, but I consider those too fragile for permanent installation. Should be able to tap manifold and clear out any metal bits by removing carb only, and not having to open the manifold which requires resealing the intake tubes

David A.

[sonex892.]

Whoops. After reading Daves reply I found and read the hacman installation manual. I have to eat my word's here. To my surprise the hacman does infact go to the vacuum port.

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[Cess32cw]

To David’s point I am wondering if the “scaling” might be off on my Dynon Skyview. I went out to the airport last night and looked for ways to alter or “set” the baro pressure internally to a known value. Couldn’t find anything but with all of the different menu’s and sub menu’s I may have missed something. I did disconnect the tube from the “T” fitting to the MAP sensor on the firewall. No difference in the indicated pressure. Anyone out there a Dynon Skyview guru who might jump in on this?

[woodmw]

I'd check around the airport and see if someone has an old steam gauge not in use. Plumb it in and compare the pressure to determine if scaling is the problem.