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View Poll Results: sniffle valve yes or no?
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Yes must have a sniffle valve
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40 |
66.67% |
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sniffle valve is not really needed
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20 |
33.33% |

01-31-2010, 09:58 PM
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Join Date: Sep 2006
Location: Townsend, Montana
Posts: 3,179
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Sniffle valve.... yes or no?
I've got a IO-360, AFP injection and Superior forward sump. What's the verdict on sniffle valves? needed or not?
__________________
Retired Dam guy. Life is good.
Brian, N155BKsold but bought back.
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01-31-2010, 10:19 PM
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Join Date: Nov 2007
Location: Spearfish, SD
Posts: 67
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Yep
I just went through the education process on sniffle valves. After a few chuckles regarding the nature of my inquires the verdict seemed to be that vertical sumps don't need one but horizontal sumps do. Has to do with excess fuel collecting in the sump and being a hazard for backfires etc. The vertical sumps allow the fuel to drain out the throttle servo, but the horizontal ones collect it in back of the sump which is where they put the drain hole for the sniffle valve.
Hope this helps.
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02-01-2010, 04:49 AM
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Join Date: Jan 2005
Location: Martinsville, IN
Posts: 2,326
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NOPE
Sorry to contradict Grandy, but it is not needed IF you installed the cutoff valve from AFP. If you do not have the cutoff valve, then yes, you need the sniffle. The AFP system does not fully cut off the fuel flow with the throttle fully retarded. The cutoff valve keeps the fuel in the spider from draining down into the cylinders and into the intake. I don't believe it matters which intake you have because the Rockets use a vertical sump and the fuel pools in the intake elbow where it can cause a fire if the engine backfires. I have no knowledge of horizontal sump engines.
Give Ron at AFP a call. He will be happy to answer any question you may have.
__________________
Randy Pflanzer
Greenwood, IN
www.pflanzer-aviation.com
Paid through 2043!
Lund fishing Boat, 2017, GONE FISHING
RV-12 - Completed 2014, Sold
427 Shelby Cobra - Completed 2012, Sold
F1 EVO - partially completed, Sold
F1 Rocket - Completed 2005, Sold
RV-7A - Partially completed, Sold
RV-6 - Completed 2000, Sold
Long-EZ - Completed 1987, Sold
Last edited by f1rocket : 02-01-2010 at 04:55 AM.
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02-01-2010, 08:36 PM
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Join Date: Oct 2006
Location: torrance, ca
Posts: 650
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NO
You really don't need one either way, purge valve or not. Unless you've got one of those plastic sumps, then... are there still some out there that haven't blown up yet? My -6 with an IO-360-A3B6D with Bendix injection has been happily without for 320 hours (this engine's been without for 2320 hours) and I haven't missed it yet. No clue why so many folks are so adamant that you MUST have one. In fact, see parts catalog below, MOST of the injected horizontal sump engines DID NOT come with one originally.
Of course, if you're superstitious, then by all means install one...

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02-02-2010, 07:50 AM
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Join Date: Jan 2005
Location: Martinsville, IN
Posts: 2,326
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You have a Bendix injection, not a AFP. They don't work the same and they are not interchangable. I'm not superstitious, I just called AFP and spoke to someone who knows the differences.
The other option is to leave the sniffle valve off and see if pooling fuel is a problem on your install. You can always install the sniffle valve later.
__________________
Randy Pflanzer
Greenwood, IN
www.pflanzer-aviation.com
Paid through 2043!
Lund fishing Boat, 2017, GONE FISHING
RV-12 - Completed 2014, Sold
427 Shelby Cobra - Completed 2012, Sold
F1 EVO - partially completed, Sold
F1 Rocket - Completed 2005, Sold
RV-7A - Partially completed, Sold
RV-6 - Completed 2000, Sold
Long-EZ - Completed 1987, Sold
Last edited by f1rocket : 02-02-2010 at 08:05 AM.
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02-02-2010, 09:51 AM
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Join Date: Jan 2005
Location: Las Vegas, NV
Posts: 488
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I sure like my sniffle valve
on hot starts (superior io360 180hp, horizontal cold air sump). Sniffle valve makes it hard to really flood the engine by draining excess fuel. A "flooded" hot start process works great every time.
Throttle & Mix in.
boost pump for a couple seconds
Mix out and crank till it catches.
Mix in and Throttle back to idle
boost pump on as req'd to keep running.
The sniffle valve makes this easy cause no overly large quantity of fuel can remain in the sump.
THE BAD THING about the sniffle valve is the pool of fuel & oil on the hangar floor after every flight. Plan on running tubing from the sniffle valve aft to drain it at a convenient spot.
__________________
Terry F.
RV 7A N457RV
250 hours and lovin it! 
Southern Nevada EAA Chapter 1300 - www.eaa1300.org
Paid VAF 03/17
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02-02-2010, 10:39 PM
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Join Date: Jan 2005
Location: Georgetown, TX
Posts: 396
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I have a horizontal sump with a sniffle valve and experience the oil/fuel drips. What I don't understand is where the oil part of the drainage is coming from...seepage from the intake valve guides?
__________________
Deene Ogden.
N399AD RV-12...flying
N299AD RV8 QB, IO-390X, BA prop...SOLD
N199AD One Design...SOLD
N99AD BD4, flew for 22 years...SOLD
EAA Tech Counselor/Flight Advisor
CFII, MEI, CFIG
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02-03-2010, 07:00 PM
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Join Date: Jan 2005
Location: Las Vegas, NV
Posts: 488
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Intake guides
are the only source I can think of for the oil that ends up on the floor. Without a sniffle valve, this oil would eventually end up going back through the engine. Probably not a bad thing (top end oil). It's a little bit of a mess but I like the fact that I don't dump lots of extra fuel through the engine on a hot start...
__________________
Terry F.
RV 7A N457RV
250 hours and lovin it! 
Southern Nevada EAA Chapter 1300 - www.eaa1300.org
Paid VAF 03/17
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02-12-2010, 08:31 AM
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Join Date: Dec 2006
Location: Shalimar, Fl
Posts: 37
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I did not install a sniffle valve when I built my RV7 and was lucky I did not ruin my engine. I was in St Louis one time and had to delay my takeoff due to very heavy blowing rain of several hours duration. When I went to start my engine, the prop rotated about half a turn and stopped. I got out and tried to pull it by hand but it would not turn. I took the cowling off and could not see anything wrong. Tried starter again with same result. I didn't know what else to try so I removed a plug from each cylinder and imagine my surprise when water came out of one cylinder. The engine was hydrolocked. I was lucky cause if one cylinder had fired up, I probably would have bent a connecting rod or worse. Anyway, I removed the plug that I had installed in the sniffle valve hole, drained a bunch or water out, pulled the prop through several times to get water out of the cylinders, started it up and all was well.
I have the Vans vertical induction on my IO360 that goes to the front of the baffle and had never heard of a sniffle valve till I called Vans and informed them of what happened. I bought a sniffle valve and also suggested that they put something an the RVator but they never did.
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02-12-2010, 11:05 AM
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Join Date: Mar 2008
Location: KDVT, AZ
Posts: 132
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I install a sniffle valve.
The ECI Horizontial induction had a red plastic plug in the location of the sniffle valve when my engine arrived. I could either plug it or install the valve. I choise to install the valve. 
__________________
Chris
RV-7A
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