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  #11  
Old 02-21-2021, 09:37 PM
622BH 622BH is offline
 
Join Date: Nov 2011
Location: Albany, OR
Posts: 170
Default Interesting...

Dan, NOT an argument; when I followed the Van's installation manual and components with the old conventional FI system there was a call for a hole to be drilled in the firewall flange that was to hold the tube from the "Sniffle Valve" (their words) that was attached to the mechanical fuel pump. Thus my response above.
However, with the two FlyEFII FI systems there's no call for a sniffle valve at all. With a bit of experience starting the engine, I've found the risk of over fueling an engine (priming) is reduced. But indeed it can happen.
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  #12  
Old 02-21-2021, 10:13 PM
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rocketbob rocketbob is offline
 
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Location: 8I3
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Default

Quote:
Originally Posted by DanH View Post
BTW, although very, very uncommon, in the automotive world sometimes injectors do leak, filling a cylinder with fuel and bending a rod on the subsequent startup. Got a picture of a bent 6.0L Chevy truck rod around here somewhere...
On the Porsche M96 engines as injectors age they leak down at shutdown. The fuel dribbles down into the bottoms of the cylinders which dilutes the oil and causes bore scoring.
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  #13  
Old 02-22-2021, 05:23 AM
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Larry DeCamp Larry DeCamp is offline
 
Join Date: Apr 2010
Location: Clinton, Indiana
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Default Auto transition from ROP to LOP ?

Please educate me regarding the risks and benefits. I have one of those SWITCHES to accomplish the task.
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  #14  
Old 02-22-2021, 08:13 AM
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DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
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Quote:
Originally Posted by 622BH View Post
Dan, NOT an argument; when I followed the Van's installation manual and components with the old conventional FI system there was a call for a hole to be drilled in the firewall flange that was to hold the tube from the "Sniffle Valve" (their words) that was attached to the mechanical fuel pump. Thus my response above.
I hear ya'. Do note most installations run a tube from the sniffle valve on the bottom of the intake system to an attach point at the base of the firewall.

An engine-driven fuel pump has a tell-tale vent, but the vent has no valve, just a micro-diameter restrictor insert. It also gets a hose to the base of the firewall.

Quote:
However, with the two FlyEFII FI systems there's no call for a sniffle valve at all. With a bit of experience starting the engine, I've found the risk of over fueling an engine (priming) is reduced. But indeed it can happen.
I agree the fuel pooling risk is lessened with any EFI. However, here the OP asked about a sniffle on a Superior manifold, which has no real plenum volume or sump (see below). All pooled liquid is going straight to a cylinder. EFI or not, it needs a sniffle valve.
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Last edited by DanH : 02-22-2021 at 08:17 AM.
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  #15  
Old 02-22-2021, 10:50 AM
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riseric riseric is offline
 
Join Date: Oct 2011
Location: CNV9
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Default Rain water

Quote:
Originally Posted by DanH View Post
the OP asked about a sniffle on a Superior manifold, which has no real plenum volume or sump (see below). All pooled liquid is going straight to a cylinder. EFI or not, it needs a sniffle valve.
-

Thanks Dan for your insight, very appreciated!!
I hadn't considered rain water...

Sorry for questionning what now seems evident, I just wish to fully understand.
The sniffle valve is closed when the engine is running so no draining when flying through rain.
Water pooling could then occur when parked outside, rain water entering through the cowl inlet, down the snorkel and into the sump???
Even though a 1/8" to 3/16" drain hole is at the lowest point in the snorkel??

Installing the sniffle would be at the arrow in the attached photo??
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  #16  
Old 02-22-2021, 12:22 PM
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DanH DanH is offline
 
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Quote:
Originally Posted by riseric View Post
The sniffle valve is closed when the engine is running so no draining when flying through rain.
Correct, but nothing will pool in the manifold in flight, and the engine won't care about water fed into it as drops and vapor.

Quote:
Water pooling could then occur when parked outside, rain water entering through the cowl inlet, down the snorkel and into the sump???
Even though a 1/8" to 3/16" drain hole is at the lowest point in the snorkel??
That is indeed the purpose of the drain hole...but it doesn't take much to clog the typical 1/8" opening. It's happened.

Quote:
Installing the sniffle would be at the arrow in the attached photo??
Yes.
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  #17  
Old 02-23-2021, 09:12 AM
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riseric riseric is offline
 
Join Date: Oct 2011
Location: CNV9
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Default

Quote:
Originally Posted by DanH View Post
Correct, but nothing will pool in the manifold in flight, and the engine won't care about water fed into it as drops and vapor.



That is indeed the purpose of the drain hole...but it doesn't take much to clog the typical 1/8" opening. It's happened.



Yes.
Many thanks Dan, appreciate your time !
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Emp & Wings installed, Fuselage in progress
Grove Airfoiled Gear, Wheels & Brakes
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EarthX batteries
Aerosport IO-375 & MTV-9-B/183
Skyview HDX in progress
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