Sniffle Valve Normal Operation Question

UnPossible · #1 05-08-2012, 09:36 PM

Hey - one more question.... tonight I put fuel in the tanks, primed the fuel pump and tested the fuel system. Once it primed, my fuel pressure was in the green (don't remember the specific numbers - but they were green!).

I ran the pump for several seconds inorder for the pressure to stabalize. When I got out of the plane, I noticed a decent amount of fuel coming out of the drain line for the sniffle valve.

I believe that it is just doing its job (draining excess fuel out of the sump) but wanted to double check to make sure that this is not something I need to worry about.

Thanks,
Jason

scsmith · #2 05-09-2012, 12:16 AM

Just because you built up fuel pressure, doesn't mean hardly any fuel should get into the intake manifold (sump) that easily.

I prime my IO-360 by running the boost pump for 4 seconds with the mixture full rich and the throttle wide open. That seems like just the right amount of prime for a cold engine.

If you had the mixture at idle-cut-off and you ran the boost pump up to pressure, and got fuel in your intake manifold, enough to drip out of your sniffle valve, then I wonder if you have a problem with your fuel servo, or at the very least, inspect your mixture linkage to make sure you are getting to idle cut-off.

socal · #3 07-19-2012, 05:08 PM

Hi Steve I have new IO360 Lyc 180hp CS FWF kit with std Vetterman exh.
Sniffle valve has 1/16 (or less) clearence from #1 exh pipe.
I have heard of some guys just not using them at all, whats your take.
No real help from Van's or Vetterman, he says remote it. Van's says Gee we don't know why.
Also throttle cable bracket goes over exhaust but not enough room for heat shield. I think Iam just going to have to modify bracket but don't understand why I should. I am not the first RV8A. Once again Van's is basically dodging the issue, saying all Lycoming engines are diff. Not so according to Lyc.
Thx for your thoughts Al

AltonD · #4 07-19-2012, 05:42 PM

I like mine. It drains the intake manifold if I flood it. I have done so on a few occasions. I did get the PiperSniffle valve. It makes a 90 degree turn after. The one Van's sold me hits the exhaust onthe IO-360-M1B with the vetterman's exhaust.

http://www.vansairforce.com/communit...=sniffle+piper

Bavafa · #5 07-20-2012, 12:05 AM

Quote:

Originally Posted by AltonD

I like mine. It drains the intake manifold if I flood it. I have done so on a few occasions. I did get the PiperSniffle valve. It makes a 90 degree turn after. The one Van's sold me hits the exhaust onthe IO-360-M1B with the vetterman's exhaust.

http://www.vansairforce.com/communit...=sniffle+piper

True, but you can just buy a 45degree fitting and put the sniffle valve on that. I have the M1B engine and vetterman's exhaust and was able to use the standard sniffle valve. As mentioned, it can be of a great deal of help if you flood the engine. Well worth the $$$

rzbill · #6 07-20-2012, 04:30 AM

+1 for the 45 degree fitting stated by Mehrdad.
It turns an unaccepable install (too close to ex pipe) into a beautiful thing.

Steve is also correct to be concerned about injection servo leakage. However, if there is preservative oil in the intake (there was a lot in my M1B from Vans/Lyc) the valve will drip enough oil to notice for the first 5 to 10 starts.