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sniffle valve in RV 7A

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yenduc(at)sbcglobal.net
Guest

Posted: Wed May 07, 2008 5:12 pm Post subject: sniffle valve in RV 7A

from Dave Cudney RV 7A struggler



 	  Quote: 	
		   I am getting further along with my project and was just buttoning up  

 a few odds an ends when I came to the sniffle valve for my IO 369.   

 On the tail dragger there is not much of a problem routing the drain  

 line from the sniffle valve --- but on the nose dragger, the nose  

 gear bracing on the engine mount is in the way.  Has any one out  

 there solved this problem and what did you do?


	


Thanks in advance

dave

 	  Quote:

Mark Phillips in TN

Joined: 10 Jan 2006
Posts: 431
Location: Columbia, TN

Posted: Wed May 07, 2008 6:50 pm Post subject: sniffle valve in RV 7A

In a message dated 05/07/2008 8:14:16 PM Central Daylight Time, yenduc(at)sbcglobal.net writes:

  	  Quote: 	
		  Has any one out  

 	  Quote: 	
		   there solved this problem and what did you do? 	


 On a recently installed valve on an Aerosport IO-360 with AFP injection mounted to forward sump (-7A), I had more of a problem getting the drain tube away from the Vetterman crossovers.  I cut the tube from the sniffle valve fairly short (1"?) and soldered a brass 90 deg. fitting to it.  The other end of this fitting (from the aviation plumbing aisle at Lowes) provided for connection for a copper tube the same size as from the sniffle valve (1/8"?) using a brass compresion ferule.  I installed the valve, then bent/routed a copper tube from the 90 aft, securing it mid-length to the exhaust hangar cross-piece and extended it aft out the air outlet so that when it drips (which it WILL) the fuel will simply drop to the ground rather than down the nose gear fairing and onto the pant.
	


  

 Not sure if this will help with your situation, but it may offer some options...

  

 From The PossumWorks in TN

 Mark

 http://websites.expercraft.com/n51pw/



Wondering what's for Dinner Tonight? Get new twists on family favorites at AOL Food.

  [quote][b]

_________________
From The PossumWorks...

yenduc(at)sbcglobal.net
Guest

Posted: Wed May 07, 2008 9:52 pm Post subject: sniffle valve in RV 7A

Thanks --- I've got one of those aviation plumbing stores close by -- I'll try your method.



dave



On May 7, 2008, at 7:47 PM, Fiveonepw(at)aol.com (Fiveonepw(at)aol.com) wrote: 	  Quote: 	
		    In a message dated 05/07/2008 8:14:16 PM Central Daylight Time, yenduc(at)sbcglobal.net (yenduc(at)sbcglobal.net) writes:

  	  Quote: 	
		  Has any one out  

 	  Quote: 	
		   there solved this problem and what did you do? 	


 On a recently installed valve on an Aerosport IO-360 with AFP injection mounted to forward sump (-7A), I had more of a problem getting the drain tube away from the Vetterman crossovers.  I cut the tube from the sniffle valve fairly short (1"?) and soldered a brass 90 deg. fitting to it.  The other end of this fitting (from the aviation plumbing aisle at Lowes) provided for connection for a copper tube the same size as from the sniffle valve (1/8"?) using a brass compresion ferule.  I installed the valve, then bent/routed a copper tube from the 90 aft, securing it mid-length to the exhaust hangar cross-piece and extended it aft out the air outlet so that when it drips (which it WILL) the fuel will simply drop to the ground rather than down the nose gear fairing and onto the pant.
	


  

 Not sure if this will help with your situation, but it may offer some options...

  

 From The PossumWorks in TN

 Mark

 http://websites.expercraft.com/n51pw/



Wondering what's for Dinner Tonight? Get new twists on family favorites at AOL Food.

  	  Quote: 	
		  

href="http://www.matronics.com/Navigator?RV-List">http://www.matronics.com/Navigator?RV-List

href="http://forums.matronics.com">http://forums.matronics.com

href="http://www.matronics.com/contribution">http://www.matronics.com/contribution



	


	


 [quote][b]

rv9jim(at)juno.com
Guest

Posted: Thu May 08, 2008 5:31 am Post subject: sniffle valve in RV 7A

I guess I am missing something.  With fuel injection, you will not have

fuel "dripping" down into the air box.  The sniffle valve is necessary

with a carburator style fuel system.  With that system you can cause raw

fuel to exceed the ability of the engine to ingest it.  Especially if you

have an accelertor pump on the carb. That will possibly let fuel run back

into the air filter box.  Am I in error?  I have AFP system and it has

the fuel purge system which will take off all fuel pressure in the shut

down phase.  During a starting phase the fuel is placed just in front of

the intake valve and "should" all be ingested.  



Jim Nelson

IO-360

yenduc(at)sbcglobal.net
Guest

Posted: Thu May 08, 2008 6:48 am Post subject: sniffle valve in RV 7A

On an IO 360 with horizontal induction  mounted forward of a cold air  

sump, small amounts of gas can pool in the sump after shutdown.  A  

sniffle valve is used to drain these few drops.

On May 8, 2008, at 6:25 AM, James H Nelson wrote:



 	  Quote: 	
		   



 I guess I am missing something.  With fuel injection, you will not  

 have

 fuel "dripping" down into the air box.  The sniffle valve is necessary

 with a carburator style fuel system.  With that system you can cause  

 raw

 fuel to exceed the ability of the engine to ingest it.  Especially  

 if you

 have an accelertor pump on the carb. That will possibly let fuel run  

 back

 into the air filter box.  Am I in error?  I have AFP system and it has

 the fuel purge system which will take off all fuel pressure in the  

 shut

 down phase.  During a starting phase the fuel is placed just in  

 front of

 the intake valve and "should" all be ingested.



 Jim Nelson

 IO-360

stein(at)steinair.com
Guest

Posted: Thu May 08, 2008 8:15 am Post subject: sniffle valve in RV 7A

Actually you can and will sometimes have fuel drain back down the intake

tubes with an injected system.  Prime it for a few seconds too long and

it'll start dribbling, and sometimes on shutdown you can get a wee bit as

well.  It's standard practice to at least put a "weep hole" in the FAB or

somewhere at the low point to make sure fuel doesn't pool where you don't

want it.



My 2 cents as usual.



Cheers,

Stein



[quote]--

yenduc(at)sbcglobal.net
Guest

Posted: Thu May 08, 2008 5:59 pm Post subject: sniffle valve in RV 7A

The sniffle valve I got from Superior with my engine sucks.  Or more  

properly does not seal well under suction ( I can detect a slight leak  

when I check it by blowing backwards on it).  I believe Dan Checkoway  

told me he replaced his with a better one but I lost my notes.  Anyone  

have a sniffle valve source?



Thanks

dave

On May 8, 2008, at 9:11 AM, SteinAir, Inc. wrote:



[quote] 



 Actually you can and will sometimes have fuel drain back down the  

 intake

 tubes with an injected system.  Prime it for a few seconds too long  

 and

 it'll start dribbling, and sometimes on shutdown you can get a wee  

 bit as

 well.  It's standard practice to at least put a "weep hole" in the  

 FAB or

 somewhere at the low point to make sure fuel doesn't pool where you  

 don't

 want it.



 My 2 cents as usual.



 Cheers,

 Stein



> --

Mark Phillips in TN

Joined: 10 Jan 2006
Posts: 431
Location: Columbia, TN

Posted: Thu May 08, 2008 6:38 pm Post subject: sniffle valve in RV 7A

In a message dated 05/08/2008 8:33:29 AM Central Daylight Time, rv9jim(at)juno.com writes:

  	  Quote: 	
		  I guess I am missing something.  With fuel injection, you will not have

fuel "dripping" down into the air box.  The sniffle valve is necessary

with a carburator style fuel system.  With that system you can cause raw

fuel to exceed the ability of the engine to ingest it.  Especially if you

have an accelertor pump on the carb. That will possibly let fuel run back

into the air filter box.  Am I in error?  I have AFP system and it has

the fuel purge system which will take off all fuel pressure in the shut

down phase.  During a starting phase the fuel is placed just in front of

the intake valve and "should" all be ingested.  	


 >>>

  

 Yes, but only while the engine is cranking.  When opened, the purge valve routes all fuel back to wherever it is plumbed, and prevents any from entering the engine via the spider when it is open, which is very useful to run cool fuel through the entire system with the boost pump on to help avoid vapor lock if the engine is hot.  BUT- any time the boost pump is on (even is mixture control is at idle cut-off), "some" fuel is being discharged from the injectors.  If not ingested by the cylinders by cranking the engine, it simply runs down the intake tubes into the "sump" (actually, the manifold under the oil sump) and will accumulate there.  Hence the need to drain it via the sniffle valve.  Careful control of the boost pump and purge valve will mitigate this drainage, but ultimately some fuel will wind up in the manifold.  The AFP system will always "leak" fuel at the injectors if the purge valve is closed and there is fuel pressure, hence the need for the valve.  This is one reason the purge valve is necessary, since pulling mixture to ICO will possibly not shut down a running engine as some fuel is still getting through the injectors.  Opening the purge valve is the only way to completely shut all fuel flow off to the injectors.  (Well, you could always shut off the fuel supply from the tanks or run them dry...)

  

 On a carbureted engine, pumping the throttle will definately shoot raw gas into the intake and if the engine is not cranking, this fuel would fall back into the air box, potentially creating a fire hazard.  I never pump the throttle on my carbureted engine unless it is cranking for this very reason.

  

 Are you currently running your AFP equipped engine?  If so, what is your start procedure, cold & hot?

  

 Mark

  

  



Wondering what's for Dinner Tonight? Get new twists on family favorites at AOL Food.

  [quote][b]

_________________
From The PossumWorks...

Mark Phillips in TN

Joined: 10 Jan 2006
Posts: 431
Location: Columbia, TN

Posted: Thu May 08, 2008 7:19 pm Post subject: sniffle valve in RV 7A

In a message dated 05/08/2008 9:01:55 PM Central Daylight Time, yenduc(at)sbcglobal.net writes:

  	  Quote: 	
		  Or more  

properly does not seal well under suction ( I can detect a slight leak  

when I check it by blowing backwards on it). 	


 >>>

  

 I performed the same test on the valve I received in Vans FWF kit and it did the same as you describe.  Concerned about this, I contacted tech support and was informed this was normal and the tiny amount of leakage would have no discernable effect.  Consider the total amount of air consumed by the engine against the amount of air leaking past the valve.  The engine (Aerosport IO-360) performed quite nicely with this valve installed both while engine running and while draining...

  

 Mark



Wondering what's for Dinner Tonight? Get new twists on family favorites at AOL Food.

  [quote][b]

_________________
From The PossumWorks...

rv9jim(at)juno.com
Guest

Posted: Fri May 09, 2008 5:15 am Post subject: sniffle valve in RV 7A

Hi Mark,

        I am "running" a IO-360 and I chose to not install a sniffle

valve.  My first start shoud be in a few weeks.  So the proceedure used

will be adapted for the purge valve style operation.  I have about 5 or 6

things to finish up and then get it blessed with paper work.  Then I

should be ready to go fly   ))



Jim

Don

Joined: 18 Jan 2006
Posts: 13

Posted: Fri May 09, 2008 1:45 pm Post subject: Re: sniffle valve in RV 7A

[quote="yenduc(at)sbcglobal.net"]The sniffle valve I got from Superior with my engine sucks.  Or more  

properly does not seal well under suction ( I can detect a slight leak  

when I check it by blowing backwards on it).  I believe Dan Checkoway  

told me he replaced his with a better one but I lost my notes.  Anyone  

have a sniffle valve source?



Thanks

dave

We make manifold drains (sniffel valves).  You can attach a #4 hose to this part to route the fuel away from the exhaust and out the cowling.  In a tight installation where the part cannot hang straight down, you can install a 90 degree pipe fitting to the sump and run a hose back to the manifold drain.  As long as the little check ball can fall open when the engine is off it will work.



The P/N is 1090138 $17.00.



Don at Airflow Performance.

Paul Valovich

Joined: 11 Jan 2006
Posts: 75

Posted: Sat May 10, 2008 7:50 am Post subject: sniffle valve in RV 7A

I purchased a new IO-360 from Aerosport. It had provisions for a sniffle valve, so I installed it. Pretty much a no-brainer installation, although I haven’t reached the first engine start page yet.  

   

Am I missing something? What’s the downside of having a sniffle valve?   

   

My plane will be based at Inyokern in the middle of the Mojave Desert. Summer heat will be an issue. Seemed to me, anything that helped prevent vapor lock problems was ok.  

Paul Valovich  

RV-8A N192NM LuJaRo  

Wiring 99% done – canopy is next  

      [quote][b]

mr.sun

Joined: 30 Jan 2007
Posts: 85

Posted: Sat May 10, 2008 8:24 am Post subject: sniffle valve in RV 7A

I installed a sniffle valve on my 4 year old RV-7 after speaking to the Aerosport folks.  I've been having hot start- flooding issues IO-360 w/forward facing induction.  The problem is gone now and it starts every time.  However, I can't say whether the solution was the new battery I installed, the valve or my improved starting technique.  Unfortunately, I couldn't  get the valve installed in the rear of the sump so a little gas sits there after a hot shut-down.  I know this because I can lift the tail and see a bit of fuel drip out from the sniffle valve.  There are two spots to install the valve on my engine but the rear spot isn't usable due to exhaust components, etc.    Just some info.

 

Do not Archive



On Sat, May 10, 2008 at 8:46 AM, Valovich, Paul <pvalovich(at)dcscorp.com (pvalovich(at)dcscorp.com)> wrote:

[quote]                

I purchased a new IO-360 from Aerosport. It had provisions for a sniffle valve, so I installed it. Pretty much a no-brainer installation, although I haven't reached the first engine start page yet.  

   

Am I missing something? What's the downside of having a sniffle valve?   

   

My plane will be based at Inyokern in the middle of the Mojave Desert. Summer heat will be an issue. Seemed to me, anything that helped prevent vapor lock problems was ok.  

Paul Valovich  

RV-8A N192NM LuJaRo  

Wiring 99% done – canopy is next  

       	  Quote: 	
		  



t="_blank">http://www.matronics.com/Navigator?RV-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	




[b]

_________________
Greg RV-7

Mark Phillips in TN

Joined: 10 Jan 2006
Posts: 431
Location: Columbia, TN

Posted: Sat May 10, 2008 7:37 pm Post subject: sniffle valve in RV 7A

In a message dated 05/10/2008 10:52:54 AM Central Daylight Time, pvalovich(at)dcscorp.com writes:

  	  Quote: 	
		  Seemed to me, anything that helped prevent vapor lock problems was ok. 	


 I really don't believe the sniffle valve has anything to do with vapor lock- it is only to allow raw fuel that can accumulate in the intake manifold between the fuel servo and the intake tubes to drain.  By design in an injected engine, there SHOULD be no fuel in this area- fuel should only enter the intake airstream at the injector and pass immediately to the cylinder.  In the AFP system I am familiar with, if the fuel system is pressurized by the boost pump and the engine is not cranking, some fuel will discharge from the injector nozzles and run down the intake tubes into the manifold.  This is the reason for the sniffle valve- to allow this fuel to drain from this area where it is not meant to be.  Is it "bad" to have some fuel pooling here?  I don't know, but I doubt normal engine running airflow would cause much to be ingested into the engine.  It would likely remove itself after "some" period of time by simple evaporation into the airstream.

  

 Some might look at the sniffle valve as a band-aid for less-than-ideal understanding & operation of the injection system, but in my experience if you leave the boost pump running for more than 5 or 10 seconds when the engine is not running or cranking (purge valve closed) there WILL be fuel running out the sniffle valve and deposited wherever gravity dictates.

  

 The AFP system is an excellent fuel delivery system in wide use, but just like that stick poking up between your legs, if not used as it was intended to be used, it can cause you some measure of grief.

  

 It appears Don checks this list occasionally, so if I am in error, PLEASE correct & elaborate.

  

 Mark



Wondering what's for Dinner Tonight? Get new twists on family favorites at AOL Food.

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_________________
From The PossumWorks...

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