VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics


Go Back   VAF Forums > RV Firewall Forward Section > Traditional Aircraft Engines
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #11  
Old 05-15-2019, 04:06 PM
tgmillso tgmillso is offline
 
Join Date: Nov 2012
Location: Launceston, Tasmania, Australia
Posts: 689
Default

My red cube was under reading quite significantly when using the default calibration values, so much so that the fuel flow was registering as below the lower limit for the engine on takeoff (red cube between the servo and spider). It wasn't until a couple of flights that I was able to re-calibrate the red cube in the G3X, and sure enough the fuel flow is now smack bang in the middle of published range.
I wouldn't spend too much time beating it up on the ground glazing cylinders and risking stone chips. Just get it ready, ensure your baffles are as good as they possibly can be (go to town on the Permatex Ultra in any gap you can find between the AL baffles and the engine), go fly and keep that nose down on climbout (130kts) to ensure good cooling during the break in. I did my first oil change at 5hrs, a second at 25hrs then switched from break-in oil to W100+ at 50hrs and saw a 25degF drop in CHT (although unfortunately no speed gain). I did the first few hard running break-in flights using 100LL Avgas, then switched to BP 98RON mogas since.
Good luck.
Tom.
RV-7
IO-360M1B with dual PMAG
Reply With Quote
  #12  
Old 05-15-2019, 06:06 PM
sglynn's Avatar
sglynn sglynn is offline
 
Join Date: Mar 2008
Location: Anacortes, WA
Posts: 771
Default

Thank you for your numbers Steve. How did you adjust and check the engine gets 16G/H at full power before first flight?

RV74ME
I didn't check for 16GPH before first flight other than running the AUX Pump and measuring fuel at the hose going into the "Integrator / servo" which showed 40 gph. I figured with this kinda of test the only thing left that could have starved the engine of fuel was plugged nozzles. So the only thing I did was run full throttle for about 20 seconds on the runway prior to take off. It held full power fine. The brakes could hardly hold it. So I took off because of the need to break-in the engine before glazing the cylinder walls. I took a photo of the panel during climb out and that's how I know what the numbers are. Here is link to that photo.

https://www.dropbox.com/s/7rctgy4675...11933.jpg?dl=0


But I know how you are "thinking" or "feeling" about this first flight and fuel flow. My runway ends at the Pacific Ocean so was my RV going to get me to 500 feet and out over the ocean and then stop running? It was possible. PS, the ocean is 40F in Puget Sound. I did wear a life preserver. I did have ground crew. I did not have Coast Guard, but probably should have.

I did communicate with Lycoming and they reminded me that the NEW engine had been run and tested at their factory and that it is ready to run for 10 hours before any oil change. They reminded me this is not like a field rebuilt engine that needs more testing. They assured me that if I got fuel to the Integrator or servo the rest of the engine would run. So . . . I'm glad that first flight is complete.
__________________
Steve Lynn
RV-7A
Flying Phase I
Anacortes, WA
www.mykitlog.com/sglynn

Last edited by sglynn : 05-15-2019 at 06:16 PM.
Reply With Quote
  #13  
Old 05-15-2019, 06:43 PM
DanH's Avatar
DanH DanH is online now
 
Join Date: Oct 2005
Location: 08A
Posts: 8,472
Default

Quote:
Originally Posted by RV7ForMe View Post
I could disconnect the line at the spider and let the pump do its job with the red cube still connected. If the G3X matches the 3.x G/H I can measure with a bucket and see if its the same?
That would check the accuracy of the red cube.

Quote:
Are these red cubes accurate over the entire spread? I want it to be accurate at about 14 gal but I cant test that with the engine off? correct? In other words are we sure if it is accurate between 3-4 G/H it will be at 14-16?
Correct.

Quote:
This led me to believe I do not fully understand the works of the fuel servo. I understand it mixes air and fuel.
No fuel-air mixing in the servo. The servo meters fuel to the flow divider (the spider), which delivers it to a nozzle at each intake port.

Quote:
When the engine is off even with the pump trying to pump 46 G/H it only lets 3.6 G/H pass?
Correct

Quote:
Is the ram air pressure needed for the fuel servo to work properly?
Ram and pressure drop from a venturi. Some info here:

https://www.danhorton.net/Articles/B...yond%20(1).pdf

Quote:
But what is the "proper" process in adjusting and testing the engine gets what it needs before first flight?
You've already checked fuel delivery to the servo. Check for full travel of the throttle and mixture arms. Adjustments are generally limited to idle mixture and idle RPM. Full rich mixture is set on a test lab bench, not in the field.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
  #14  
Old 05-16-2019, 03:23 AM
MGRVAwesome MGRVAwesome is offline
 
Join Date: Jul 2010
Location: Port Elizabeth, South Africa
Posts: 24
Default

Something I picked up was that my mixture knob was dead against the panel on full rich. Which meant that every time I took off at full throttle the carb would "auto-lean" due to the engine pulling slightly forward on the mountings, thereby pulling against the mixture cable. So, make 100% sure your red knob is set at about 1/8th of an inch away from the panel on full rich. That brought my temps down by about 25 degrees.
Reply With Quote
  #15  
Old 05-16-2019, 03:27 AM
RV7ForMe RV7ForMe is offline
 
Join Date: Jul 2015
Location: Europe
Posts: 453
Default Thanks

Quote:
Originally Posted by tgmillso View Post
go fly and keep that nose down on climbout (130kts) to ensure good cooling during the break in. I did my first oil change at 5hrs, a second at 25hrs then switched from break-in oil to W100+ at 50hrs and saw a 25degF drop in CHT
Alright Thanks for the Info Tom!

Quote:
Originally Posted by sglynn View Post
I didn't check for 16GPH before first flight other than running the AUX Pump and measuring fuel at the hose going into the "Integrator / servo" which showed 40 gph. I figured with this kinda of test the only thing left that could have starved the engine of fuel was plugged nozzles.
Ok. understood.

Quote:
Originally Posted by sglynn View Post
But I know how you are "thinking" or "feeling" about this first flight and fuel flow.

I did communicate with Lycoming and they reminded me that the NEW engine had been run and tested at their factory and that it is ready to run for 10 hours before any oil change. They reminded me this is not like a field rebuilt engine that needs more testing. They assured me that if I got fuel to the Integrator or servo the rest of the engine would run. So . . . I'm glad that first flight is complete.
Ok this does make me feel a little better. I just didn't want it to run lean on first flight

Quote:
Originally Posted by DanH View Post
That would check the accuracy of the red cube.
OK this I will do next.

Quote:
Originally Posted by DanH View Post
No fuel-air mixing in the servo. The servo meters fuel to the flow divider (the spider), which delivers it to a nozzle at each intake port.
Thanks.

Quote:
Originally Posted by DanH View Post
Ram and pressure drop from a venturi. Some info here:

https://www.danhorton.net/Articles/B...yond%20(1).pdf
OK This is great!!!

Quote:
Originally Posted by DanH View Post
You've already checked fuel delivery to the servo. Check for full travel of the throttle and mixture arms. Adjustments are generally limited to idle mixture and idle RPM. Full rich mixture is set on a test lab bench, not in the field.
To the best of my abilities I have done this correctly. If I can actually not adjust the full mixture I am guessing this is the reason I did not find much info on how to do it! Thanks for making it clear Dan.
__________________
VAF dues paid until 10/2019
RV7-A (N137MX Reserved) - Wings Started...
RV7-A - Rebuild Done - Flying!
Cessna Rocket 210HP - Best dang 172 Ever made! (sold)
Reply With Quote
  #16  
Old 05-16-2019, 03:28 AM
RV7ForMe RV7ForMe is offline
 
Join Date: Jul 2015
Location: Europe
Posts: 453
Default WOW!

Quote:
Originally Posted by MGRVAwesome View Post
Something I picked up was that my mixture knob was dead against the panel on full rich. Which meant that every time I took off at full throttle the carb would "auto-lean" due to the engine pulling slightly forward on the mountings, thereby pulling against the mixture cable. So, make 100% sure your red knob is set at about 1/8th of an inch away from the panel on full rich. That brought my temps down by about 25 degrees.
I never thought about this! thank you.
__________________
VAF dues paid until 10/2019
RV7-A (N137MX Reserved) - Wings Started...
RV7-A - Rebuild Done - Flying!
Cessna Rocket 210HP - Best dang 172 Ever made! (sold)
Reply With Quote
  #17  
Old 05-16-2019, 12:06 PM
jabarr jabarr is online now
 
Join Date: Sep 2008
Location: Fayetteville, Georgia
Posts: 202
Default

Why are you only getting 23.8 inches at full throttle. Are you getting full travel on the throttle linkage? Are you at a high elevation?
Reply With Quote
  #18  
Old 05-16-2019, 12:10 PM
RV7ForMe RV7ForMe is offline
 
Join Date: Jul 2015
Location: Europe
Posts: 453
Default

Quote:
Originally Posted by jabarr View Post
Why are you only getting 23.8 inches at full throttle. Are you getting full travel on the throttle linkage? Are you at a high elevation?
This is not full throttle it was at 2570 RPM. Full throttle should be around 2700 RPM and no we are at 400feet it was about all the brakes will hold
__________________
VAF dues paid until 10/2019
RV7-A (N137MX Reserved) - Wings Started...
RV7-A - Rebuild Done - Flying!
Cessna Rocket 210HP - Best dang 172 Ever made! (sold)
Reply With Quote
  #19  
Old 05-16-2019, 12:24 PM
Bavafa Bavafa is offline
 
Join Date: Oct 2007
Location: Sacramento, CA
Posts: 2,785
Default

If any thing, in addition to these recommendation, I recommend to check the timing of you ignition. That is something that is well worth checking and could have an effect on the CHT temp.
__________________
Mehrdad
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying
Dues paid
Reply With Quote
  #20  
Old 05-16-2019, 12:35 PM
RV7ForMe RV7ForMe is offline
 
Join Date: Jul 2015
Location: Europe
Posts: 453
Default

Quote:
Originally Posted by Bavafa View Post
If any thing, in addition to these recommendation, I recommend to check the timing of you ignition. That is something that is well worth checking and could have an effect on the CHT temp.
I believe that one is correct but I will put it on the list and recheck again. Thank you
__________________
VAF dues paid until 10/2019
RV7-A (N137MX Reserved) - Wings Started...
RV7-A - Rebuild Done - Flying!
Cessna Rocket 210HP - Best dang 172 Ever made! (sold)
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 04:28 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.