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Engines-List Digest: 1 Msgs - 04/20/10

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Speedy11(at)aol.com
Guest

Posted: Wed Apr 21, 2010 12:24 pm Post subject: Engines-List Digest: 1 Msgs - 04/20/10

Monty,

 Thanks for your response and your explanation - that was exactly the info I  needed.

 I was referring to the plenum, but another guy had called it the sump, so I  called it that thinking my terminology was wrong.

 The engine is running great - only a few minor hiccups.  I have some  surging during taxi.  I'm not sure what is causing it, but I probably need  to adjust the idle.  And I have a minor, but aggravating, oil leak that  we're tracing.  Local A&P is going to wash the engine and I'll do  multiple engine runs to try and local the leak.

 I'll add the sniffle valve you mentioned.

 Thanks,

 Stan Sutterfield

  [quote]It is    common for some oil to be in the plenum.  The sump itself is    full

of  oil so I suspect you are referring to the plenum, which is    part of

the induction system and is below the sump.



The reason that    there is some oil in there is because when the engine is

operated at slow    speed, such as taxi speed, the rocker boxes get

overfilled with oil, more    so on a fresh engine where the ball sockets of

the pushrods have not bedded    themselves to each corresponding rocker.

Then when the engine shuts down    the oil in the rocker box will  run thru

the intake guide, down the    inlet pipe to the plenum, assisted by some

fuel which, when shutdown,    will  " dribble " out of the fuel nozzle,

diluting the oil and    lowering is viscosity.  Then the fuel evaporates

leaving the oil    residue.



There are 1/8 NPTF holes in the lower edge of the plenum in    which a "

sniffle valve " should be installed.  Put a sniffle valve in    the lower

port when the aircraft is sitting on the ground.  This valve    is used to

drain off residual fuel and oil.  It's primary purpose is    to minimize an

induction fire during a balked start.  Use the one made    by Airflow

Performance which has 1/8 NPTM thread on one end and -4 flare on    the

other.  Run a line overboard from underneath the    cowling.



Monty Barrett

Barrett Precision Engines, Inc.



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rv8a2001(at)yahoo.com
Guest

Posted: Wed Apr 21, 2010 1:32 pm Post subject: Engines-List Digest: 1 Msgs - 04/20/10

Surging at idle when hot is boiling of the fuel in the injector lines......at least for me. Very annoying in the summer time!

 

Scott

RV-8a

 



 

   From: "Speedy11(at)aol.com" <Speedy11(at)aol.com>

To: engines-list(at)matronics.com

Sent: Wed, April 21, 2010 1:23:53 PM

Subject: Re: Engines-List Digest: 1 Msgs - 04/20/10



 Monty,

 Thanks for your response and your explanation - that was exactly the info I needed.

 I was referring to the plenum, but another guy had called it the sump, so I called it that thinking my terminology was wrong.

 The engine is running great - only a few minor hiccups.  I have some surging during taxi.  I'm not sure what is causing it, but I probably need to adjust the idle.  And I have a minor, but aggravating, oil leak that we're tracing.  Local A&P is going to wash the engine and I'll do multiple engine runs to try and local the leak.

 I'll add the sniffle valve you mentioned.

 Thanks,

 Stan Sutterfield

  [quote]It is common for some oil to be in the plenum.  The sump itself is full

of  oil so I suspect you are referring to the plenum, which is part of

the induction system and is below the sump.



The reason that there is some oil in there is because when the engine is

operated at slow speed, such as taxi speed, the rocker boxes get

overfilled with oil, more so on a fresh engine where the ball sockets of

the pushrods have not bedded themselves to each corresponding rocker.

Then when the engine shuts down the oil in the rocker box will  run thru

the intake guide, down the inlet pipe to the plenum, assisted by some

fuel which, when shutdown, will  " dribble " out of the fuel nozzle,

diluting the oil and lowering is viscosity.  Then the fuel  evaporates

leaving the oil residue.



There are 1/8 NPTF holes in the lower edge of the plenum in which a "

sniffle valve " should be installed.  Put a sniffle valve in the lower

port when the aircraft is sitting on the ground.  This valve is used to

drain off residual fuel and oil.  It's primary purpose is to minimize an

induction fire during a balked start.  Use the one made by Airflow

Performance which has 1/8 NPTM thread on one end and -4 flare on the

other.  Run a line overboard from underneath the cowling.



Monty Barrett

Barrett Precision Engines, Inc.



    --

- The Matronics Engines-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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