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Sniffle Valve on Carbureted Engine

CABaye

I'm New Here
Newbie Question:

The O-360-A1A in my new-to-me RV-6A is equipped with a Sniffle Valve. This part on a carbureted engine seems contrary to the guidance for use. Being new to RV's, are there other useful reasons to have the valve on this engine?

- Chris
 
Newbie Question:

The O-360-A1A in my new-to-me RV-6A is equipped with a Sniffle Valve. This part on a carbureted engine seems contrary to the guidance for use. Being new to RV's, are there other useful reasons to have the valve on this engine?

- Chris

Is the valve in the airbox, or somewhere on the intake. For the airbox, it makes sense. Though I just drilled a small drain hole, the sniffle valve seems like overkill.
 
Thanks for post

Thanks for bring this topic up. I just did a bunch of research and figured I dont need one on my engine. I figure any excess fuel will seep out my alternate air door. One less thing to put together.
 
Correct. Not needed on the carberuated engines. It is needed on the injected engines with the snorkel, as fuel does drain past the spyder after shutdown and into the cylinders. This allows the fuel to drain out of the bottom of the intake.

Those engines with the updraft/vertical induction systems do not need it, as the fuel just drains into the airbox. Make sure you have the drain holes in the airbox.

Vic
 
It is needed on the injected engines

With one minor exception - those of us that have installed the SDS or EFII systems with electronic injection. Those are positive-stop systems and won't drain fuel on shutdown, hence no need for the sniffle valve.
 
With one minor exception - those of us that have installed the SDS or EFII systems with electronic injection. Those are positive-stop systems and won't drain fuel on shutdown, hence no need for the sniffle valve.

I believe it's also not needed for the engines with the Airflow Performance bypass valve systems - at least that's my limited experience, nothing substantial coming out of the sniffle valve. Unless of course you leave your aircraft out in the rain, and you fill up the intake with water...
 
I believe it's also not needed for the engines with the Airflow Performance bypass valve systems - at least that's my limited experience, nothing substantial coming out of the sniffle valve. Unless of course you leave your aircraft out in the rain, and you fill up the intake with water...

I ran a standard Bendix injection with the AFP purge valve for a few years before installing the SDS. It definitely reduced the amount of boil-out, but you still dump the volume of fuel that is in the divider itself and in the spider lines. That's enough, in my opinion, to warrant the sniffle valve on that setup - at least I left mine in place. YMMV.
 
I ran a standard Bendix injection with the AFP purge valve for a few years before installing the SDS. It definitely reduced the amount of boil-out, but you still dump the volume of fuel that is in the divider itself and in the spider lines. That's enough, in my opinion, to warrant the sniffle valve on that setup - at least I left mine in place. YMMV.

Absolutely agree that fuel still runs down from the lines.

As well as it is needed for parking in the rain. We had one that was parked in extrememly heavy rain in Florida. The intake can hold a substantial amount of water.

Vic
 
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