VansAirForceForums  
Home > VansAirForceForums

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

- Today's Posts | Insert Pics


Go Back   VAF Forums > Model Specific > RV-12
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #11  
Old 06-18-2016, 09:18 PM
Tony_T's Avatar
Tony_T Tony_T is offline
 
Join Date: Dec 2008
Location: Seattle, WA
Posts: 1,140
Default

I bought a twin engine manifold pressure gauge on eBay. They show the use of one of these on the Rotax Owner website.
__________________
Tony
RV-12 #202 -- Flying
Reply With Quote
  #12  
Old 06-28-2016, 01:55 PM
HansLab HansLab is offline
 
Join Date: Jan 2015
Location: Netherlands
Posts: 42
Default Best

Two for the plastic and bottle solution: I build a gauge of two bottels and some hoses that worked great! Just functie the cards until the two bottles contain equal amounts of water. Fun to make and I loved to work with it. Google on carb's and synchronisation.
Spend the money to something that will give you advantage.
__________________
Hans Labruyere
build & sold project Kitfox IV
Bought project & building RV12 #120742
Reply With Quote
  #13  
Old 08-05-2017, 03:45 PM
AirHound AirHound is offline
 
Join Date: Oct 2006
Location: OFallon IL now, everywhere before
Posts: 132
Default Need to learn how to use carbmate. ROAN videos don't explain what side to adjust

Quote:
Originally Posted by RFSchaller View Post
I use the electronic Carb Mate from California Power Systems, but at the ROTAX course the instructor had a neat setup using a manifold pressure gage from a twin engine aircraft. He just adjusted the carbs to get the gage needles on top of each other.
__________________
Doug
Reply With Quote
  #14  
Old 08-05-2017, 05:15 PM
John-G John-G is offline
 
Join Date: Jan 2012
Location: Northeast Ohio
Posts: 427
Default

Quote:
Originally Posted by AirHound View Post
:Need to learn how to use carbmate. ROAN videos don't explain what side to adjust
Doug ... when using the CarbMate one carb becomes the "reference" and the other carb is adjusted to match it. It really does not matter which carb is the reference as long as the other carb is adjusted to match the vacuum of the reference carb at idle and the high RPM range .... and, of course, the final idle speed should be within the desired specs. When the center light is on and you are on the high sensitivity setting, the carbs will truly be balanced to each other.

A tool like the CarbMate is just fine for synchronizing the carbs, however, the bad thing about using a device like the CarbMate is it is not well suited for trouble shooting because one really does not know what the actual vacuum levels are. If everything is OK with the engine & carbs and all you are doing is synchronizing them, then using a device like the CarbMate is just fine ... however, if you are having issues, it does not lend itself well for troubleshooting problems. This is one reason why I have both the CarbMate and gauges.

About the gauges, if one is inclined to order a pair ... don't make the same mistake I did when asleep at the wheel late one night clicking away ordering two vacuum gauges that were "0-30 inches of water" gauges. The inches of water gauges I accidentally ordered were DESTROYED a few seconds after the engine started .... an expensive mistake. Make sure the gauges are 0-30 inches of mercury and NOT inches of water. I can laugh about it now, but it was NOT funny at the time.
__________________
John
www.dogaviation.com
RV-12 Wings, Empennage, Fuselage, Finishing, Avionics and Powerplant kits all completed
Now Flying!!

Dues paid until September 2017

Last edited by John-G : 08-05-2017 at 05:19 PM.
Reply With Quote
  #15  
Old 08-05-2017, 07:00 PM
AirHound AirHound is offline
 
Join Date: Oct 2006
Location: OFallon IL now, everywhere before
Posts: 132
Default

Quote:
Originally Posted by John-G View Post
Doug ... when using the CarbMate one carb becomes the "reference" and the other carb is adjusted to match it. It really does not matter which carb is the reference as long as the other carb is adjusted to match the vacuum of the reference carb at idle and the high RPM range .... and, of course, the final idle speed should be within the desired specs. When the center light is on and you are on the high sensitivity setting, the carbs will truly be balanced to each other.

A tool like the CarbMate is just fine for synchronizing the carbs, however, the bad thing about using a device like the CarbMate is it is not well suited for trouble shooting because one really does not know what the actual vacuum levels are. If everything is OK with the engine & carbs and all you are doing is synchronizing them, then using a device like the CarbMate is just fine ... however, if you are having issues, it does not lend itself well for troubleshooting problems. This is one reason why I have both the CarbMate and gauges.

About the gauges, if one is inclined to order a pair ... don't make the same mistake I did when asleep at the wheel late one night clicking away ordering two vacuum gauges that were "0-30 inches of water" gauges. The inches of water gauges I accidentally ordered were DESTROYED a few seconds after the engine started .... an expensive mistake. Make sure the gauges are 0-30 inches of mercury and NOT inches of water. I can laugh about it now, but it was NOT funny at the time.
John-G, thank you! Here's my read back. Do the mechanical sync procedure first, then for the pneumatic procedure pick a side as REF and make all carb cable adjustments on just the opposite side in whatever direction that moves the red dot to the green in the center. Do this procedure for 2000, 3000, 4000 and at each RPM level make adjustments on each charbmate setting down to .05?
Am I close? Oh and then once Nurvana is achieved make final idle stop adjustments. ?
__________________
Doug
Reply With Quote
  #16  
Old 08-05-2017, 08:22 PM
John-G John-G is offline
 
Join Date: Jan 2012
Location: Northeast Ohio
Posts: 427
Default

Doug - You have the general idea ....

I would suggest trying to first get an idle speed that is in the ballpark using Van's suggested idle speed range. Moving forward, while adjusting the non-reference carb, should the idle RPM go up or down tweak the idle accordingly then verify the carbs are still in sync at the idle speed you've chosen. You will find yourself going back and forth a few times. After you get the carbs close at idle, continue to the off idle synchronization.

For the high RPM I have read here and elsewhere that a little higher RPM than the 3,000 you mentioned is better for the off-idle adjustment because it insures the carbs are out of the idle circuit ... think I used 3,900 RPM which seems to have worked well. When you think about it this engine will typically either be operating at 1,800 to 2,100 when on the ground or well above 4,000 RPM in the air.
__________________
John
www.dogaviation.com
RV-12 Wings, Empennage, Fuselage, Finishing, Avionics and Powerplant kits all completed
Now Flying!!

Dues paid until September 2017
Reply With Quote
  #17  
Old 08-05-2017, 08:59 PM
RFSchaller RFSchaller is offline
 
Join Date: Oct 2010
Location: Phoenix, AZ
Posts: 2,041
Default

I use a Carbmate. I just suck on one of the sensor hoses each time to see which way the lights go and use the fact that the high suction side is the low load side.
Reply With Quote
  #18  
Old 08-05-2017, 09:01 PM
AirHound AirHound is offline
 
Join Date: Oct 2006
Location: OFallon IL now, everywhere before
Posts: 132
Default

Quote:
Originally Posted by John-G View Post
Doug - You have the general idea ....

I would suggest trying to first get an idle speed that is in the ballpark using Van's suggested idle speed range. Moving forward, while adjusting the non-reference carb, should the idle RPM go up or down tweak the idle accordingly then verify the carbs are still in sync at the idle speed you've chosen. You will find yourself going back and forth a few times. After you get the carbs close at idle, continue to the off idle synchronization.

For the high RPM I have read here and elsewhere that a little higher RPM than the 3,000 you mentioned is better for the off-idle adjustment because it insures the carbs are out of the idle circuit ... think I used 3,900 RPM which seems to have worked well. When you think about it this engine will typically either be operating at 1,800 to 2,100 when on the ground or well above 4,000 RPM in the air.
Ok! Sounds to me, once center green/idle is lit up and let's just say 1800, then go 3800 but am I correct about making adjustments only on the nonREF side and doing them in each of carbmates 3 settings? Don't mean to nail it down here just looking for a proven jumping off point and the how. It's amazing how little there really is out there on the the web that goes into detail. I do believe it's easy as many say, but there's unwritten method to the madness for carbmate too. Sure wis others would pipe up to clue me in too. Thanks John G I'll take all with a grain of salt and get some experience. V/r Doug
__________________
Doug
Reply With Quote
  #19  
Old 08-05-2017, 09:19 PM
AirHound AirHound is offline
 
Join Date: Oct 2006
Location: OFallon IL now, everywhere before
Posts: 132
Default

Quote:
Originally Posted by RFSchaller View Post
I use a Carbmate. I just suck on one of the sensor hoses each time to see which way the lights go and use the fact that the high suction side is the low load side.
Hey Rich, high suction and low load side, what then, ? Make cable adjustments on that side only? Thank you!
__________________
Doug
Reply With Quote
  #20  
Old 08-06-2017, 12:23 AM
Gandalf Gandalf is offline
 
Join Date: Apr 2008
Location: Medford, OR
Posts: 261
Default

Just for fun:





Old school, triple side draft SU carbs, complete with oil pots
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 11:58 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.