Geico266

Geico266

Well Known Member
RV-10
Page FF1-6
PN# VA-170


Make sure you use the correct size plastic tubing as called out in the drawing for the subject fitting. PN VA-170 has a tiny hose barb on the end and uses plastic tubing #PT .093 x .156 only. NOT 1/4"OD x 1/8"ID. The note on the print says you should change the fitting if you use something different other than Van's MP guage. IMHO it should be replaced with a threaded fitting ASAP. Using 1/4"O.D x 1/8"ID tubing may / will cause a serious vacuum leak.

Pay particular attention to this "situation" if you fly with an electronic ignition(s). If you have a MP vacuum leak the EI may advance the spark too far - or - too little for the actual engine power setting, causing high temps, loss of engine power, and / or possible damage to the engine.

I found this situation on my RV-10, IO-540 @ 215 Hours.

JMHO.
 
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Larry, wouldn't a leak in a vacuum system cause it to read higher, not lower? Higher "reading" = retarding of spark.. not advance.... just curious..
 
I don't think that's correct. you'd blow up the engine by advancing too much at high power settings

someone had posted advance curve for one of the EIs... I think it was Jeff Rose's.. but they all do the same thing more or less..sorry, don't have the link handy now.. hope someone can jump in and post it..
 
I don't think

Thats quite right...At least as far as Emags go, max manifold pressure means wide open..But in that case max timing is limited to a max of 25deg..

Its at low manifold pressure the spark is allowed to advance to 36 degrees I think thats what I got mine set to.

Either way we still don't want a leak

Frank
 
Radomir said:
Larry, wouldn't a leak in a vacuum system cause it to read higher, not lower? Higher "reading" = retarding of spark.. not advance.... just curious..
Click to expand...

You are missing the point.

Please don't let such a serious thread get bogged down with trivial minutia. The point is a MP system vacuum leak can bring your plane down if you are using an EI. If you have dual EI's and are using the same MP source you may have a very serious flaw in your ignition system. Please make sure your MP system is secure and you don't use the hose barb fitting supplied in the Van's kit. A leak in the MP system may bring you down.

I have tried to contact the mfg and ask them about this with no joy, so my only choice is is say nothing and risk someone getting killed or say something and risk being wrong. I hope I'm wrong.



JMHO
 
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In all fairness to Vans thier fitting and for that matter that small plastic tube was never intended to be used in any way but to run a MP gauge not to run an EI system.
 
Check out this thread

I was having difficulties connecting that little tube from the bulkhead fitting to the manifold sensor. Ran across this thread and orderd a different bulkhead fitting from Aircraftspruce.

Don't know how to put a thread link it but here is the title. Look down about 4-5 threads and check out the photo and explanation from Cytoxin.

Dynon Manifold Pressure Weatherpack
 
Rivethead said:
In all fairness to Vans thier fitting and for that matter that small plastic tube was never intended to be used in any way but to run a MP gauge not to run an EI system.
Click to expand...

You are exactly right, and explained it better than I did.

If I came across as bashing Vans I appoligize. The note on the print is very specific about that. If you use something other than Van's MP guage then you need to use a different fitting. Threaded is the only way to go IHMO.
 
Webb said:
I was having difficulties connecting that little tube from the bulkhead fitting to the manifold sensor. Ran across this thread and orderd a different bulkhead fitting from Aircraftspruce.

Don't know how to put a thread link it but here is the title. Look down about 4-5 threads and check out the photo and explanation from Cytoxin.

Dynon Manifold Pressure Weatherpack
Click to expand...

http://www.vansairforce.com/communi...highlight=Dynon+Manifold+Pressure+Weatherpack

That fitting is still a "slip" type. How does the hose connect to be vacuum tight?
 
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Dunno about the bulkhead fitting, but the fittings on my Lightspeed control boxes and the Blue Mountain Engine Pod are barb type slip-on. Lightspeed supplied Tygon tubing with their system. Because I don't trust other types of line to work well over the barb fittings, I'll use their material but, since I have to 'tee' the lines I will be using compression fittings at the tees and a spare bit of pitot/static line to go from the flare at the (new) bulkhead fitting and the first tee fitting. My biggest worry is how the Tygon will hold up forward of the firewall; I will have the penetration as close to the Engine Pod as possible and keep it close to the firewall.
 
Clamp it

Geico266 said:
http://www.vansairforce.com/communi...highlight=Dynon+Manifold+Pressure+Weatherpack

That fitting is still a "slip" type. How does the hose connect to be vacuum tight?
Click to expand...

Put one of those little spring hose clamps on it. We're dealing with low, not high pressures here. The clamp is designed to keep the hose from slipping off, not to seal. The elasticity of the hose keeps the connection. I guess I could hook it up to my air compressor, turn up the regulator slowly, and measure the pressure at which the seal fails. However, since I am hearing it is a vaccum line, I don't have a vaccum pump to test the force needed to break the seal loose. Common sense tells me that a vaccum would be harder to break loose than pressure and that little Tygon tubing would colapse much earlier than the seal would break.

Personally, I didn't like the little Tygon tube because of the how easily it vibrated due to the small diameter of the tube and I was concerned about vibration induced structural failure of the tube. In addition, I was having dfficulty with transition to the manifold sensor's connection

To your point of not getting going down the technical road....Do a good job of making the connection so you won't have problems later.......
 
In my instance there will be a Dynon EMS and a set of LAZAR mags run off of my MP pressure source. This picture shows what I've done to solve the problem. In the end end I use only a few parts supplied by Van. That Aluminum tube isn't necessarily the way it will end up but is a good start.

hybmp.jpg
 
Rivethead said:
In my instance there will be a Dynon EMS and a set of LAZAR mags run off of my MP pressure source. This picture shows what I've done to solve the problem. In the end end I use only a few parts supplied by Van. That Aluminum tube isn't necessarily the way it will end up but is a good start.

hybmp.jpg
Click to expand...

I did almost the same thing-------used a bulkhead "T" with a short piece of 1/4" aluminum tube over toward the Lazar box, mounted on firewall, final connection there with an inch or so of hose.

I used the barbed mini tube fitting inside the boot cowl, screwed into the bulkhead "T", MP sensor for the GRT mounted on a rib, and about 6" of tube to connect it.
 
For the sake of discussion, let me offer another alternative. You don't even need a bulkhead fitting. Here's what I did. Firswt let me apologize that I don't have any pictures of this. I'll do my best to explain.

1) I ran the manifold line from cylinder 5 (that's cylinder 3 for you 4-bangers) to one of those manifold brackets that Van's sells. It's the thing that you can screw in all your senders and run the hoses to them.

2) From there, I ran a copper 1/8" compression fitting and 1/8" copper tubing in with my wiring bundle through a fireproof firewall passthrough fitting.

3) On the instrument panel side of the firewall, I slipped on Tygon tubing that fit tightly over the copper tubing and secured it with tie wraps. You can't pull it off because I pulled pretty hard.

I thought this was pretty simple and clean. I struggled to find the right approach to get manifold pressure back inside the cockpit and considered a bulkhead fitting too, but this turned out well enough that I'm using the same method again.
 
Question

Since I have one of those steel fittings with reduced opening in it installed on cylinder #3 (thats #5 for you 6 bangers - lol), can I just pipe it on through to the sensor? My guess is straight on through to sensor.

Also, the Van's firewall fitting for the Tygon tubing - reducer, tubing hookup, or both? Myguess is both.
 
f1rocket said:
1) I ran the manifold line from cylinder 5 (that's cylinder 3 for you 4-bangers) to one of those manifold brackets that Van's sells. It's the thing that you can screw in all your senders and run the hoses to them.

2) From there, I ran a copper 1/8" compression fitting and 1/8" copper tubing in with my wiring bundle through a fireproof firewall passthrough fitting.

3) On the instrument panel side of the firewall, I slipped on Tygon tubing that fit tightly over the copper tubing and secured it with tie wraps. You can't pull it off because I pulled pretty hard.
Click to expand...

Confusious say cat can be skinned in many ways.

Good idea Randy.
 
Yep. Interesting this came up when it did; I did mine today. Here's my nekkid cat:

DSC01360.jpg

This is Van's fitting on the cylinder and his hose to a standard bulkhead fitting. Dunno why the engine looks orange; it's really red. Must be a camera flash effect.

DSC01359.jpg


Ok, here's the meat of it. Leftover pitot line flared on aft side of firewall curves around to "tee" compression fitting. By the way, I tried normal 1/4" line (the kind used for refrigerator drains, etc.) from Home Depot and I could not tighten the fitting enough to keep the tube in place. Whatever tubing you use, test it. My pitot/static tubing came with my wing kit a dozen years ago; no guarantee that the stuff Van's ships now is the same. Anyway, mine will destroy the tube before pulling out of the fitting. I continue to the next "tee" with the same material, and then through the firewall to connect to the Blue Mountain Engine Pod.

The connections to the Lightspeed ECI boxes are with the supplied Tygon line. This stuff was a real bear to get into the compression fitting and is equally difficult to get out. I found that putting enough through the nut to be flush with the open end and then pressing the insert back into the tube worked best; the tube and seated insert would be slightly inside the nut and I could just get the nut started on the fitting. Tightening the nut pressed the insert and tubing back into place. Then the tubing was cut to length and pressed over the barb fittings in the ECI boxes.

DSC01361.jpg


There's the final connection; an oxy quick-connect into the Engine Pod. The grommet at the firewall will get a shield. No the braided line is not really connected to the Pod; it's the fuel pressure line, capped and awaiting hookup to it's transducer. Anyway, hopefully this will be the most complex MP setup anyone will have to deal with.
 
Geico266 said:
You are missing the point.

Please don't let such a serious thread get bogged down with trivial minutia. The point is a MP system vacuum leak can bring your plane down if you are using an EI. If you have dual EI's and are using the same MP source you may have a very serious flaw in your ignition system. Please make sure your MP system is secure and you don't use the hose barb fitting supplied in the Van's kit. A leak in the MP system may bring you down.

I have tried to contact the mfg and ask them about this with no joy, so my only choice is is say nothing and risk someone getting killed or say something and risk being wrong. I hope I'm wrong.



JMHO
Click to expand...

Larry, people are not getting bogged down with minutia -

I have no concerns if the MAP line to my dual Lightspeed ignitions falls off. The timing will go to baseline (usually 25 BTDC) if it happens near sea level. Higher altitudes will go to whatever timing that would be commanded with a wide open throttle. I do not see any scenario that the MAP line to an EI is critical in any way. Good practice is to put a restrictor in the line right at the cylinder, so that if the MAP line breaks, it won't cause such a lean cylinder as to create mis-fire. But, I don't see the risk to EI. Please clarify what you are thinking.
 
Now that it is show-and-tell time, here is my installation (I chunked the Van's bulkhead fitting).

Fancy Tee was hanging on the wall at Autozone. I used a Van's restictor fitting on the engine (#3Cylinder)
FP09072008A0000J.jpg


FP09072008A0000I.jpg
 
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