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ROTAX 912 AIR VENT LINE

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Goodone

Joined: 13 Sep 2008
Posts: 49

Posted: Sun Feb 01, 2009 6:54 am Post subject: ROTAX 912 AIR VENT LINE

I want to lengthen the carburetor AIR VENT LINE a bit on my Rotax 912 powered aircraft but I do not know the size line (plastic tubing) that is used. This is a Bing Constant Depression Carb used on all 912's. I live about 1 hour from my aircraft (near hardware stores) and would appreciate any information that can be provided a lot.

larry(at)macsmachine.com
Guest

Posted: Sun Feb 01, 2009 9:54 am Post subject: ROTAX 912 AIR VENT LINE

Good morning Goodone,

The part number is 236035 air vent line, 120mm (length assumed) and can 

also be

substituted for part number 861940 compensating tube. The sources for 

these parts

should be able to tell you what the diameter is if you call them.



Larry McFarland 601HDS at www.macsmachine.com

do not archive



Goodone wrote:

 	  Quote: 	
		   



 I want to lengthen the carburetor AIR VENT LINE a bit on my Rotax 912 powered aircraft but I do not know the size line (plastic tubing) that is used. This is a Bing Constant Depression Carb used on all 912's. I live about 1 hour from my aircraft (near hardware stores) and would appreciate any information that can be provided a lot.





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 27990#227990

Goodone

Joined: 13 Sep 2008
Posts: 49

Posted: Sun Feb 01, 2009 2:29 pm Post subject: Re: ROTAX 912 AIR VENT LINE

The vent line just a piece of clear plastic tubing and I want to make it a few inches longer. I am afraid that if I order it from someone like Lockwood I will be stuck with an expensive piece of clear plastic tubing that is too short (120mm) for what I want to do.

conrad

Joined: 07 Feb 2007
Posts: 16
Location: Banbury. UK

Posted: Mon Feb 02, 2009 12:49 am Post subject: Re: ROTAX 912 AIR VENT LINE

Goodone

Please do not alter these vent tubes.

They connect to the top of the float chamber. Repositioning these tubes can alter the pressure on top of the float chamber which will affect the mixture. 

They need to see the atmospheric pressure in the area of the air filter.



Conrad

hgmckay

Joined: 23 May 2006
Posts: 397

Posted: Mon Feb 02, 2009 6:24 am Post subject: ROTAX 912 AIR VENT LINE

Goodone:



Conrad is exactly right about altering the location of the carb. vent line.

I don't know how your engine is set up in your airplane, but what ever the

set up is, the open end of each vent tube on the 912 must be near each of

the air filters respectively so they will be sensing the atmospheric

pressure at that point. The photo I sent you shows the position of the tubes

on my particular plane which is a fully cowled Allegro 2000.



Hugh McKay

Allegro 2000

Rotax 912UL



--

Goodone

Joined: 13 Sep 2008
Posts: 49

Posted: Mon Feb 02, 2009 6:31 am Post subject: Re: ROTAX 912 AIR VENT LINE

Conrad



I just want to extend the length of each tube about 2 or 3 inches to get the tube ends back nearer the air filter. One of the tubes now ends directly over the exhaust pipe and I don't like the thought of fuel going through the vent and dripping onto the exhaust pipe. I do not have carb drip pans at the present time. 



Thanks,



Jim

pwmac(at)sisna.com
Guest

Posted: Mon Feb 02, 2009 6:47 am Post subject: ROTAX 912 AIR VENT LINE

Conrad is correct. the location and outlet of the plastic tube must 

not be changed.

I have been told that one can put a tee on the tube at exactly the 

same height as the original tubing then on the other leg of the  tee 

one can extend it to any length. I guess the theory is correct 

pressure will be preserved. I cannot say that I have any first hand 

knowledge that this will work. Has anybody done this trick?

Paul

=========

At 12:49 AM 2/2/2009, you wrote:

 	  Quote: 	
		  



Goodone

Please do not alter these vent tubes.

They connect to the top of the float chamber. Repositioning these 

tubes can alter the pressure on top of the float chamber which will 

affect the mixture.

They need to see the atmospheric pressure in the area of the air filter.



Conrad





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p 28126#228126

larry(at)macsmachine.com
Guest

Posted: Mon Feb 02, 2009 7:21 am Post subject: ROTAX 912 AIR VENT LINE

Paul,

I did a similar thing. Letting the tube terminate in a much larger 

diameter tube to avoid suction from the reducer and long tube that 

passed just below

the firewall. Ambient pressure of the large tube allows overflowing fuel 

to get below and behind the exhaust yet doesn't pull fuel from the carb.

Larry McFarland 601HDS at www.macsmachine.com

paul wilson wrote:

 	  Quote: 	

 Conrad is correct. the location and outlet of the plastic tube must 

 not be changed.

 I have been told that one can put a tee on the tube at exactly the 

 same height as the original tubing then on the other leg of the  tee 

 one can extend it to any length. I guess the theory is correct 

 pressure will be preserved. I cannot say that I have any first hand 

 knowledge that this will work. Has anybody done this trick?

 Paul

 =========

 At 12:49 AM 2/2/2009, you wrote:

> 

> <conrad(at)conairsports.co.uk>

>

> Goodone

> Please do not alter these vent tubes.

> They connect to the top of the float chamber. Repositioning these 

> tubes can alter the pressure on top of the float chamber which will 

> affect the mixture.

> They need to see the atmospheric pressure in the area of the air filter.

>

> Conrad

>

>

> Read this topic online here:

>

> http://forums.matronics.com/viewtopic.php?p 28126#228126

>

>

ptag.dev(at)tiscali.co.uk
Guest

Posted: Mon Feb 02, 2009 7:34 am Post subject: ROTAX 912 AIR VENT LINE

Yes Paul 

I was concerned that the cowl intake area was likely to produce some ram

air effect too close the 914 filter intake so I put a "tee" in place and

pick up two pressure positions in the cowl quadrant under my intercooler

area.

Regards

Bob Harrison G-PTAG



--

rparigor(at)suffolk.lib.n
Guest

Posted: Mon Feb 02, 2009 8:05 am Post subject: ROTAX 912 AIR VENT LINE

Hi Bob (Bob(at)tiscali.co.uk)"> I was concerned that the cowl intake area was likely to produce some ram > air effect too close the 914 filter intake so I put a "tee" in place and > pick up two pressure positions in the cowl quadrant under my intercooler > area."Please clarifiy, what exactly are you plumbing on your 914 to cowl quadrant?Thx.Ron Parigoris   [quote][b]

ptag.dev(at)tiscali.co.uk
Guest

Posted: Mon Feb 02, 2009 3:11 pm Post subject: ROTAX 912 AIR VENT LINE

Hi! Ron  

I just may have “picked the grimy end of the poker” and mistaken what sensor is affected. However the one to which I refer is necessary to be located cabin side of the firewall but sense pressure at the intake.  The cowl “quadrant” is the area to the lower starboard side of the inside of the cowl which is sectioned off below the intercooler where the intake air enters the filter and the overspill passes through the intercooler heat exchanger up into the upper cowl.  

Sorry it is a bit complicated.  

Regards   

Bob Harrison.G-PTAG   

   

--

conrad

Joined: 07 Feb 2007
Posts: 16
Location: Banbury. UK

Posted: Mon Feb 02, 2009 3:38 pm Post subject: Re: ROTAX 912 AIR VENT LINE

Bob,

You are confusing people here.

What was being discussed was the carb vent tube on a 912 engine. 

They need to see atmospheric pressure near the air filter.



You have a 914 it has a rather more complicated pressure system on the float chambers. On top of that it has two pressure sensors that measure atmospheric and airbox pressures.



What does needs to be clear is that altering the pressure in the float chamber on a bing 64 will alter the mixture no matter which engine you have.



Conrad.

ptag.dev(at)tiscali.co.uk
Guest

Posted: Tue Feb 03, 2009 4:11 am Post subject: ROTAX 912 AIR VENT LINE

Thanks for that Conrad.

I had realized my misunderstanding of the original thread but I guess I

made it more complicated with my reply.

Regards

Bob Harrison.



--

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