REFLECTOR: Update on N173VS static RPM

[Grover McNair]

Try swapping the injectors on #2 and #3. If the temps follow the injector,
you know you have an uneven flow from those two injectors. I would also
recommend rechecking the timing. You apparently have plenty of fuel and can
regulate it to the proper mixture. The only things left are air flow and
timing. An intake leak could cause one cylinder to be lean. If it were a car
I would check for a clogged catalytic converter.

Grover McNair

 

  _____  

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Jeff Barnes
Sent: Thursday, February 23, 2012 8:50 AM
To: geoff.gerhardt at gmail.com; Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Update on N173VS static RPM

 


anything blocking your air intake ?

--- On Thu, 2/23/12, Geoff Gerhardt <geoff.gerhardt at gmail.com> wrote:


From: Geoff Gerhardt <geoff.gerhardt at gmail.com>
Subject: REFLECTOR: Update on N173VS static RPM
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Date: Thursday, February 23, 2012, 6:37 AM

As I've described, I recently started up my engine for the first time.
After sorting out some minor issues with the EI, when I tried to go to full
power, I was only getting ~1900RPM static.  Also, I could only reach this
power when I pulled the mixture lever way back - the engine sputtered when
both the throttle and mixture were all the way in. 

 

On Tuesday night, I discovered that one of my fuel injector lines was
leaking at the connection to the injector (bad solder joint).  I repaired
this and tried it again last night.  But, before I did, I pulled all the
injectors out, turned the fuel pump on and observed their spray.  I measured
their volume output over a 10s period and they were all approximately equal.
So, I started it up hoping all problems were solved, but it behaved exactly
the same.  This time, though, I was a bit more observant of some of the
engine data.  

 

First thing I noticed was that the Dynon Skyview indicated it was running
very rich.  I forget exactly what the number was, but it was something like
30% ROP.  By pulling the mixture back at full throttle I could maximize
power and the Dynon did show the mixture going from very rich to
perfect/slightly lean (I forget exactly what mixture full power was
reached).  But, my static RPM was still only ~1850-1900 RPM.  It was neat to
see the EGT's bounce around very quickly to these mixture adjustments, tho.

 

The second thing I noticed was the CHT's - #3 was running significantly
colder and #2 hotter than ~#1/4.  Here's a snapshot of the temps at one
point from 1:341, 2:409, 3:290, 4:381.  Generally, 1/4 tracked pretty
closely, but #2 got pretty hot and #3 was always at least 50deg colder than
1/4.

 

Just an update on the history on the engine - it was a 500hr SMOH engine
that I bought from another Velocity owner who was parting out his plane.
He's an A&P who had bought the engine, pulled off the jugs, inspected the
crank, replaced the rings and had it running on his velo and taxing around.
He ensures it was running well and I'm taking his word on this.  Since then,
the engine's been mostly sitting in my shop or hanging on my plane pickled.
This is the first startup since I've rec'd it.

 

So, I'm going to check the plugs next.  Anyone else have any other
suggestions?

 

Thanks.

 

Geoff

 


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