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  #1  
Old 08-09-2021, 07:20 AM
larrys larrys is offline
 
Join Date: May 2017
Location: Colorado Springs
Posts: 213
Default Mixture question on first time start

First time starting it up yesterday.
We are building an RV14A with a Lycoming 390 Thunderbolt with duel Pmags and standard injection that comes on the motor.

We read the Lycoming manual and followed the steps.

In general it worked very well. But in order for it to run smooth the mixture needed to be moved a lot to accommodate the engine speed. It order to rev it up it needed more mixture. And the same with idle. But in the end it did run very smooth once it was adjusted for the range of speed. We live at 7000 elevation but it's a plane so it should not matter.

We have not done a fuel flow test yet but it measured fuel flow on the AFS screens and the pressure looked reasonably. And when the electric pump was on it seemed to pump too much pressure and you can hear it working well.

The question is it seems that it wants to run very lean and an adjustment is needed in the mixture/flow/pressure to allow for RMP/speed. On other injected planes I have flown the mixture "knob" is out about 1" + - and it just runs (at least at first rolling on the ground and starting run up). In our plane the mixture is about 1/2" from full off. And it constantly needs to be adjusted just to run well.

Does anyone have ideas to try?
Thanks, Larry
__________________

RV-14 tail, QB Fuselage, Finish kit, QB wings and FF kit, Thunderbolt 390, Hartzell C/S Blended Airfoil. Just need to finish... 90% left to go
Grateful to pay dues 21'

[/size]
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  #2  
Old 08-09-2021, 08:51 AM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest
Posts: 1,721
Default broken in

Quote:
Originally Posted by larrys View Post
First time starting it up yesterday.
We are building an RV14A with a Lycoming 390 Thunderbolt with duel Pmags and standard injection that comes on the motor.

We read the Lycoming manual and followed the steps.

In general it worked very well. But in order for it to run smooth the mixture needed to be moved a lot to accommodate the engine speed. It order to rev it up it needed more mixture. And the same with idle. But in the end it did run very smooth once it was adjusted for the range of speed. We live at 7000 elevation but it's a plane so it should not matter.

We have not done a fuel flow test yet but it measured fuel flow on the AFS screens and the pressure looked reasonably. And when the electric pump was on it seemed to pump too much pressure and you can hear it working well.

The question is it seems that it wants to run very lean and an adjustment is needed in the mixture/flow/pressure to allow for RMP/speed. On other injected planes I have flown the mixture "knob" is out about 1" + - and it just runs (at least at first rolling on the ground and starting run up). In our plane the mixture is about 1/2" from full off. And it constantly needs to be adjusted just to run well.

Does anyone have ideas to try?
Thanks, Larry
seems like it is not broken in and there is a lot of oil in the combustion chamber. i think you are trying to keep the plugs from fouling with all that oil in there. i would see if it improves in subsequent runs. I would expect to see a noticeable improvement on the second and third run prior to first flight. But I think Lycoming recommends to keep ground runs to a minimum.
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John S

WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

Dues paid 2021, worth every penny

RV9A- Status:
95% done, 15% left to go
Electrical/Panel 95% done
Firewall Forward 5% in work
Fiberglass 0%, thought i was building in metal?
www.pilotjohnsrv9.blogspot.com
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  #3  
Old 08-09-2021, 10:04 AM
Mike S's Avatar
Mike S Mike S is offline
Senior Curmudgeon
 
Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 16,052
Default Congratulations!!!

Quote:
Originally Posted by larrys View Post
First time starting it up yesterday.
We are building an RV14A with a Lycoming 390 Thunderbolt with duel Pmags and standard injection that comes on the motor.


Thanks, Larry
Larry, congrats on this latest milestone.

I remember talking to you about hangars 6 or 7 years ago and telling you about the RV line.

Glad you are making forward progress on the project.
__________________
Mike Starkey
VAF 909

Rv-10, N210LM.

Flying as of 12/4/2010

Phase 1 done, 2/4/2011

Sold after 240+ wonderful hours of flight.

"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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  #4  
Old 08-09-2021, 09:08 PM
AZSteve053 AZSteve053 is offline
 
Join Date: Jan 2013
Location: Payson, Arizona
Posts: 18
Default Idle Mixture may be too rich...

Many Lyc experimental engine arrive with the FI system idle mixture adjusted too rich, might explain why your have to lean so aggressively to get her to run. I have experienced this on several projects including two of my own.
+1 on clearing preservative oil from induction system too.
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  #5  
Old 08-10-2021, 05:13 AM
Jetmart's Avatar
Jetmart Jetmart is offline
 
Join Date: Sep 2019
Location: Windsor, Ontario
Posts: 391
Default

I had the exact same issues you are describing and know of 3 others who have. For some reason Lycoming after test running is changing the orientation of the idle mixture arm and then reassembling it. It cannot get in the wrong position without undoing the cotter pin and clevis. For me it was as simple as undoing the clevis, readjusting the arm in the correct orientation, reinstalling the clevis, and resetting the idle mixture. The attached picture is before it is corrected, I unfortunately don't have a pic of after, I have drawn in the proper location in black.
I have a Avstar servo and could not keep the engine running without changing the mixture and throttle at the same time. I spoke to both Avstar and Lycoming and they confirmed the problem. I would suggest looking at your orientation of your idle mixture arm and then talking to Lycoming before doing anything else. If not you will drive yourself crazy trying to find the fix.

Here is who I spoke to:
Brandon Dildine
Field Service Technical Representative
Lycoming Engines, an unincorporated operating division of Avco Corporation
Bdildine@lycoming.com +1 570-327-7279 or +1 877-839-7878


Rene Loew
AVStar Fuel Systems, Inc.
1365 Park Lane South
Jupiter, Florida 33458
Voice (561) 575-1560
Fax (561) 575-0795
renel@avstardirect.com
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Glenn Martin
Windsor, Ontario
1942 Tiger Moth
2017 Waco YMF-5
RV-14 Kit # 140694
First Flight - June 22, 2021
2021 Dues Paid

Last edited by Jetmart : 08-10-2021 at 05:20 AM.
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  #6  
Old 08-10-2021, 11:05 AM
larrys larrys is offline
 
Join Date: May 2017
Location: Colorado Springs
Posts: 213
Default I am so grateful to you all!

I was reading on VAF about another person wondering what brand and type of aircraft to start work on.

With this brain trust is there any doubt! VANS!
__________________

RV-14 tail, QB Fuselage, Finish kit, QB wings and FF kit, Thunderbolt 390, Hartzell C/S Blended Airfoil. Just need to finish... 90% left to go
Grateful to pay dues 21'

[/size]
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  #7  
Old 08-10-2021, 11:49 AM
Jetmart's Avatar
Jetmart Jetmart is offline
 
Join Date: Sep 2019
Location: Windsor, Ontario
Posts: 391
Default

Quote:
Originally Posted by larrys View Post
I was reading on VAF about another person wondering what brand and type of aircraft to start work on.

With this brain trust is there any doubt! VANS!
Can you let us know what you find? I would be curious to know if it is the same issue I had.
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Glenn Martin
Windsor, Ontario
1942 Tiger Moth
2017 Waco YMF-5
RV-14 Kit # 140694
First Flight - June 22, 2021
2021 Dues Paid
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  #8  
Old 08-10-2021, 12:40 PM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest
Posts: 1,721
Default What are you saying?

Quote:
Originally Posted by Jetmart View Post
I had the exact same issues you are describing and know of 3 others who have. For some reason Lycoming after test running is changing the orientation of the idle mixture arm and then reassembling it. It cannot get in the wrong position without undoing the cotter pin and clevis. For me it was as simple as undoing the clevis, readjusting the arm in the correct orientation, reinstalling the clevis, and resetting the idle mixture. The attached picture is before it is corrected, I unfortunately don't have a pic of after, I have drawn in the proper location in black.
I have a Avstar servo and could not keep the engine running without changing the mixture and throttle at the same time. I spoke to both Avstar and Lycoming and they confirmed the problem. I would suggest looking at your orientation of your idle mixture arm and then talking to Lycoming before doing anything else. If not you will drive yourself crazy trying to find the fix.

Here is who I spoke to:
Brandon Dildine
Field Service Technical Representative
Lycoming Engines, an unincorporated operating division of Avco Corporation
Bdildine@lycoming.com +1 570-327-7279 or +1 877-839-7878


Rene Loew
AVStar Fuel Systems, Inc.
1365 Park Lane South
Jupiter, Florida 33458
Voice (561) 575-1560
Fax (561) 575-0795
renel@avstardirect.com
Correct me if I am wrong, with the "incorrect" orientation, the mixture works backwards, it goes lean as the throttle is opened; the reorientation you describe reverses the shaft rotation as the butterfly is opened. Is that what you are saying? How does one know if the orientation, and linkage length are correct? or better yet, how does one set the orientation and linkage length?

Please help. i am going to be here in a few weeks.
__________________
John S

WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

Dues paid 2021, worth every penny

RV9A- Status:
95% done, 15% left to go
Electrical/Panel 95% done
Firewall Forward 5% in work
Fiberglass 0%, thought i was building in metal?
www.pilotjohnsrv9.blogspot.com
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  #9  
Old 08-10-2021, 12:42 PM
Nova RV Nova RV is offline
 
Join Date: Aug 2015
Location: Leesburg, VA
Posts: 572
Default

I personally know 2 people who had this reversed arm issue to the point where it was so rich even full lean on the idle adjuster was not enough until the arms were corrected by Avstar.
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Chris Moon
Leesburg, VA

CFI-I ASMEL, ATP

RV-14A kit # 140243 (flying as of 11/18)

www.mykitlog.com/chrismoon/
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  #10  
Old 08-10-2021, 12:49 PM
Jetmart's Avatar
Jetmart Jetmart is offline
 
Join Date: Sep 2019
Location: Windsor, Ontario
Posts: 391
Default

Quote:
Originally Posted by PilotjohnS View Post
Correct me if I am wrong, with the "incorrect" orientation, the mixture works backwards, it goes lean as the throttle is opened; the reorientation you describe reverses the shaft rotation as the butterfly is opened. Is that what you are saying? How does one know if the orientation, and linkage length are correct? or better yet, how does one set the orientation and linkage length?

Please help. i am going to be here in a few weeks.
No the linkage in the wrong orientation will not make the mixture backwards. It only throws the curve out considerably is what I was told. There is only two orientations it can be, one shown in the picture of it aft and one very close to down vertically. The length is determine by adjusting the idle mixture. To do this you want about a 30 - 50 rpm rise with the engine at idle and warm when you slowly pull the mixture out allowing it to shut down.
If the arm is in the aft orientation as shown in the pic reach out to Lycoming prior to adjusting anything.
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Glenn Martin
Windsor, Ontario
1942 Tiger Moth
2017 Waco YMF-5
RV-14 Kit # 140694
First Flight - June 22, 2021
2021 Dues Paid
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