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Doug Doty

Joined: 28 Oct 2011
Posts: 33
Location: Madison In

Posted: Thu Nov 03, 2011 4:00 pm Post subject: Plugs leading up worse than normal

Seems like in the last 60 to 90 days everyone at our airport is having plugs lead and or at least load up much much worse than ever before. With having recently bought my tiger I have noticed that it also needs leaned aggressively on the ground to run clean and it's best and during ground operation mag checks.  Has anyone else noticed anything similar in their area. We generally feel that we are dealing with a bad load of fuel at our airport. My plane has in the last 50 hours had the carb replaced with a reman unit and runs perfectly otherwise.



Part 2.. Having a fuel flow totalizer for the first time makes me wonder if anyone knows from memory what kind of flow #'s they might generally see at say, taxing rpm, runup, idle and climb out. Would be fun to compare readings here. The turbine seems to me to be accurate to within maybe as good a 1-2 tenths of a gallon on 40 gallon fill ups so it would seem to be relative to compare readings with one another. I am guilty of not knowing my own answers to these same questions but will re-post as soon as the weather breaks and I get into the air again.



I am thinking I saw 16 gallons on climb out right after liftoff but will accurize my numbers asap following my next flight.  I do not have my POH at home but does anyone know the full power climb out fuel burn expectation for the 0-360



Idle: .9 to 1 gallon



Taxi:



Run up:



Climb out:16 gallon

_________________
1977 AA5B N28454, Fuel Totalizer, Lopresti Nose, Red Rudder Cap, 4 cyl. egt, stock otherwise.

andy747(at)charter.net
Guest

Posted: Thu Nov 03, 2011 5:19 pm Post subject: Plugs leading up worse than normal

I can only provide a number for cruise but 16 GPH sounds reasonable for 

climbout.....



Time after time on four hour flights to and from my home and Chicago at 

7/8/9 T, I saw 132 knots TAS and 9.2 GPH....exactly what the charts 

predicted.... maybe one knot more or one tenth GPH on some days but 132/9.2 

was set in stone and confirmed on many flights !!!



Andy Thomas



---

david(at)troup.net
Guest

Posted: Thu Nov 03, 2011 11:46 pm Post subject: Plugs leading up worse than normal

Probably somebody else has piped in already, but if you didn't already know this, all Tigers require you to lean significantly -- I mean a lot, a couple of inches is not too much -- on the ground, to avoid lead fouling.  There's nothing unusual about that.  It's impossible to overlean on the ground, so there's basically no reason not to pull the red knob to just short of killing the engine.  I lean -- a lot -- after start and immediately after I land, when I'm turning off landing light, retracting the flaps, etc.



A side benefit of leaning aggressively on the ground is that you'll never be able to accidentally take off that way.  Your mixture knob should be far enough out that if you advance the throttle to full, the engine will stumble.  That prevents you from forgetting and taking off with the mixture too lean.



Can't speak to whether you have a bad batch of fuel or not, but there is nothing at all unusual about needing to lean on the ground.  Every Tiger I have flown will get fouled plugs almost immediately if you don't.



David Troup

Tiger N28797 (SQL)

stockercarolm(at)gmail.co
Guest

Posted: Fri Nov 04, 2011 2:22 am Post subject: Plugs leading up worse than normal

Thanks for that note...a big help!

Carol 

N28742



On Fri, Nov 4, 2011 at 3:43 AM, David Troup <david(at)troup.net (david(at)troup.net)> wrote:

 [quote]--> TeamGrumman-List message posted by: David Troup <david(at)troup.net (david(at)troup.net)>

  

 Probably somebody else has piped in already, but if you didn't already know this, all Tigers require you to lean significantly -- I mean a lot, a couple of inches is not too much -- on the ground, to avoid lead fouling.  There's nothing unusual about that.  It's impossible to overlean on the ground, so there's basically no reason not to pull the red knob to just short of killing the engine.  I lean -- a lot -- after start and immediately after I land, when I'm turning off landing light, retracting the flaps, etc.

  

 A side benefit of leaning aggressively on the ground is that you'll never be able to accidentally take off that way.  Your mixture knob should be far enough out that if you advance the throttle to full, the engine will stumble.  That prevents you from forgetting and taking off with the mixture too lean.

  

 Can't speak to whether you have a bad batch of fuel or not, but there is nothing at all unusual about needing to lean on the ground.  Every Tiger I have flown will get fouled plugs almost immediately if you don't.

  

 David Troup

 Tiger N28797 (SQL)

 

 

 

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 [b]

bkspero

Joined: 23 May 2012
Posts: 17

Posted: Thu May 24, 2012 7:25 am Post subject: Re: Plugs leading up worse than normal

 	  Doug Doty wrote: 	
		  ..... I have noticed that it also needs leaned aggressively on the ground to run clean and it's best and during ground operation mag checks...

	




I am just beginning to play with leaning on the ground.  I had been simply leaning about an inch with no attention to the effect on idle speed.  I now find that if I lean to peak idle, it takes about 1.5 inches and gains about 300 rpm over idle at full rich.



But during the ground runup mag check I go back to full rich.  Is that wrong?  Should I be leaning for that as well?  I ask because the left mag always runs a little rougher than the right during the mag check.  The RPM drop for the left mag is fine (about 80-100 rpm), and equal to the drop for the right mag.  But the left mag is noticeably rougher.



If I should be leaning for the mag check, what technique should I use (eg. run it up rich and lean until rough then enrichen slightly?)?

teamgrumman(at)yahoo.com
Guest

Posted: Thu May 24, 2012 9:35 am Post subject: Plugs leading up worse than normal

I think the old rule was to do the run up at full rich.  I've gone to leaning to near peak RPM at 1800 then doing the mag checks.  If you forget to go full rich on takeoff, it will remind you when the engine stumbles.

What plug are you running?

What gap?

        From: bkspero <bkspero(at)gmail.com>

 To: teamgrumman-list(at)matronics.com 

 Sent: Thursday, May 24, 2012 8:25 AM

 Subject: Re: Plugs leading up worse than normal

 --> TeamGrumman-List message posted by: "bkspero" <bkspero(at)gmail.com (bkspero(at)gmail.com)>

Doug Doty wrote:

 	  Quote: 	
		   ..... I have noticed that it also needs leaned aggressively on the ground to run clean and it's best and during ground operation mag checks...

I am just beginning to play with leaning on the ground.  I had been simply leaning about an inch with no attention to the effect on idle speed.  I now find that if I lean to peak idle, it takes about 1.5 inches and gains about 300 rpm over idle at full rich.

But during the ground runup mag check I go back to full rich.  Is that wrong?  Should I be leaning for that as well?  I ask because the left mag always runs a little rougher than the right during the mag check.  The RPM drop for the left mag is fine (about 80-100 rpm), and equal to the drop for the right mag.  But  the left mag is noticeably rougher.

If I should be leaning for the mag check, what technique should I use (eg. run it up rich and lean until rough then enrichen slightly?)?

Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=373771#373771

http://www.matronics.com/Navigator?TeamG                              &nbs===================

 [quote][b]

flyv35b(at)minetfiber.com
Guest

Posted: Thu May 24, 2012 12:12 pm Post subject: Plugs leading up worse than normal

On 5/24/2012 8:25 AM, bkspero wrote:



 	  Quote: 	
		   But during the ground runup mag check I go back to full rich.  Is that wrong?  Should I be leaning for that as well?  I ask because the left mag always runs a little rougher than the right during the mag check.  The RPM drop for the left mag is fine (about 80-100 rpm), and equal to the drop for the right mag.  But the left mag is noticeably rougher.



 If I should be leaning for the mag check, what technique should I use (eg. run it up rich and lean until rough then enrichen slightly?)?


	


First off you can't check the idle mixture unless the engine is fully 

warmed up (after flying).  Then you should get about a 25 rpm rise from 

full rich when you lean slowly at 800-1000 rpm, say.



I always check carb heat at full rich mixture and see about 100 rpm drop 

at 1700rpm.  I then lean to max rpm and it rises about 50 rpm or 

thereabouts.  I let it run there for 10 seconds and then do the mag 

check with it leaned.  I leave it leaned until ready to takeoff and then 

shove the mixture in.  You won't forget as the engine will stumble upon 

throttle application if you forget.  I always taxi with it leaned as far 

as the engine with still run smoothly.  I always lean in the air, even 

at low altitude, when the power is reduced for cruise.  Plugs run pretty 

clean for 100 hrs.



Cliff

bkspero

Joined: 23 May 2012
Posts: 17

Posted: Thu May 24, 2012 1:10 pm Post subject: Re: Plugs leading up worse than normal

 	  teamgrumman(at)yahoo.com wrote: 	
		  I think the old rule was to do the run up at full rich.  I've gone to leaning to near peak RPM at 1800 then doing the mag checks.  If you forget to go full rich on takeoff, it will remind you when the engine stumbles.

What plug are you running?

What gap?

[b] 	




Hi Gary.  This is about 74429.  Alan had the plugs replaced last September at about 390 hrs on the engine.  He had type REM-38E installed.  There is no entry for the gap in the logbook.  It was at about 406 hrs when I bought it, and it is at about 450 hrs now.



I will try the lean runup and see if it helps.



Barry

bkspero

Joined: 23 May 2012
Posts: 17

Posted: Thu May 24, 2012 1:19 pm Post subject: Re: Plugs leading up worse than normal

 	  flyv35b(at)minetfiber.com wrote: 	
		  



First off you can't check the idle mixture unless the engine is fully 

warmed up (after flying).  Then you should get about a 25 rpm rise from 

full rich when you lean slowly at 800-1000 rpm, say.



I always check carb heat at full rich mixture and see about 100 rpm drop 

at 1700rpm.  I then lean to max rpm and it rises about 50 rpm or 

thereabouts.  I let it run there for 10 seconds and then do the mag 

check with it leaned.  I leave it leaned until ready to takeoff and then 

shove the mixture in.  You won't forget as the engine will stumble upon 

throttle application if you forget.  I always taxi with it leaned as far 

as the engine with still run smoothly.  I always lean in the air, even 

at low altitude, when the power is reduced for cruise.  Plugs run pretty 

clean for 100 hrs.



Cliff 	




Thanks for the input, Cliff.  I now taxi lean to peak rpm.  And do lean in the air even at low altitude as long as the power is low.



Plane gives the 200+ idle rpm increase whether the engine is cold or its been flying for hours.



Makes sense to do the carb heat check while rich.  Will try the lean mag runup.  Hoping that's the key.



Thanks again.



Barry

flyv35b(at)minetfiber.com
Guest

Posted: Thu May 24, 2012 1:29 pm Post subject: Plugs leading up worse than normal

On 5/24/2012 2:19 PM, bkspero wrote:

 	  Quote: 	

 flyv35b(at)minetfiber.com wrote:

> First off you can't check the idle mixture unless the engine is fully

> warmed up (after flying).  Then you should get about a 25 rpm rise from

> full rich when you lean slowly at 800-1000 rpm, say.

>

> I always check carb heat at full rich mixture and see about 100 rpm drop

> at 1700rpm.  I then lean to max rpm and it rises about 50 rpm or

> thereabouts.  I let it run there for 10 seconds and then do the mag

> check with it leaned.  I leave it leaned until ready to takeoff and then

> shove the mixture in.  You won't forget as the engine will stumble upon

> throttle application if you forget.  I always taxi with it leaned as far

> as the engine with still run smoothly.  I always lean in the air, even

> at low altitude, when the power is reduced for cruise.  Plugs run pretty

> clean for 100 hrs.

>

> Cliff

 Thanks for the input, Cliff.  I now taxi lean to peak rpm.  And do lean in the air even at low altitude as long as the power is low.

 Plane gives the 200+ idle rpm increase whether the engine is cold or its been flying for hours.

 Makes sense to do the carb heat check while rich.  Will try the lean mag runup.  Hoping that's the key.

 Thanks again.

 Barry

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p=373807#373807

Well, your idle mixture adjustment is way to rich if you are getting 

200+ rpm rise when you lean, if your checking it with a warm engine. 

You might see that much with a cold engine right after start up.

Turn your idle mixture screw in 1/2 turn and recheck it.

Cliff

teamgrumman(at)yahoo.com
Guest

Posted: Thu May 24, 2012 9:24 pm Post subject: Plugs leading up worse than normal

If I set the plugs, I set them to .018. 

Gary

Sent from my iPad

On May 24, 2012, at 2:10 PM, "bkspero" <bkspero(at)gmail.com> wrote:

 	  Quote: 	

 teamgrumman(at)yahoo.com wrote:

> I think the old rule was to do the run up at full rich.  I've gone to leaning to near peak RPM at 1800 then doing the mag checks.  If you forget to go full rich on takeoff, it will remind you when the engine stumbles.

> 

> 

> What plug are you running?

> 

> 

> What gap?

> 

> 

> [b]

 Hi Gary.  This is about 74429.  Alan had the plugs replaced last September at about 390 hrs on the engine.  He had type REM-38E installed.  There is no entry for the gap in the logbook.  It was at about 406 hrs when I bought it, and it is at about 450 hrs now.

 I will try the lean runup and see if it helps.

 Barry

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p=373803#373803

teamgrumman(at)yahoo.com
Guest

Posted: Thu May 24, 2012 9:33 pm Post subject: Plugs leading up worse than normal

Most people check the rpm incorrectly. 

At idle, full rich, engine warm, it should idle about 600-650 rpm. Lower is better since it makes landing easier. My plane idles at 450 rpm. 

At idle, very slowly pull the mixture out.  Very slowly. The engine rpm should go up roughly 50 rpm at sea level. At 1500 feet, figure about 25-30 rpm. 

ANY throttle setting other than throttle closed at idle and the carb will NOT be operating on the idle circuit. Any checking of rpm rise without the throttle closed will give an artificially rich indication since the carb is operating on the transition circuit. 

Gary

Sent from my iPad

On May 24, 2012, at 2:19 PM, "bkspero" <bkspero(at)gmail.com> wrote:

 	  Quote: 	

 flyv35b(at)minetfiber.com wrote:

> 

> 

> First off you can't check the idle mixture unless the engine is fully 

> warmed up (after flying).  Then you should get about a 25 rpm rise from 

> full rich when you lean slowly at 800-1000 rpm, say.

> 

> I always check carb heat at full rich mixture and see about 100 rpm drop 

> at 1700rpm.  I then lean to max rpm and it rises about 50 rpm or 

> thereabouts.  I let it run there for 10 seconds and then do the mag 

> check with it leaned.  I leave it leaned until ready to takeoff and then 

> shove the mixture in.  You won't forget as the engine will stumble upon 

> throttle application if you forget.  I always taxi with it leaned as far 

> as the engine with still run smoothly.  I always lean in the air, even 

> at low altitude, when the power is reduced for cruise.  Plugs run pretty 

> clean for 100 hrs.

> 

> Cliff

 Thanks for the input, Cliff.  I now taxi lean to peak rpm.  And do lean in the air even at low altitude as long as the power is low.

 Plane gives the 200+ idle rpm increase whether the engine is cold or its been flying for hours.

 Makes sense to do the carb heat check while rich.  Will try the lean mag runup.  Hoping that's the key.

 Thanks again.

 Barry

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p=373807#373807

teamgrumman(at)yahoo.com
Guest

Posted: Thu May 24, 2012 9:35 pm Post subject: Plugs leading up worse than normal

There is a fine dance between the throttle plate setting and the mixture setting. 



Look at my web site, front page, technical, and look for setting the engine idle. 



Gary

Sent from my iPad



On May 24, 2012, at 2:28 PM, flyv35b <flyv35b(at)minetfiber.com> wrote:



 	  Quote: 	
		   

 

 On 5/24/2012 2:19 PM, bkspero wrote:

> 

> 

> 

> flyv35b(at)minetfiber.com wrote:

>> 

>> 

>> First off you can't check the idle mixture unless the engine is fully

>> warmed up (after flying).  Then you should get about a 25 rpm rise from

>> full rich when you lean slowly at 800-1000 rpm, say.

>> 

>> I always check carb heat at full rich mixture and see about 100 rpm drop

>> at 1700rpm.  I then lean to max rpm and it rises about 50 rpm or

>> thereabouts.  I let it run there for 10 seconds and then do the mag

>> check with it leaned.  I leave it leaned until ready to takeoff and then

>> shove the mixture in.  You won't forget as the engine will stumble upon

>> throttle application if you forget.  I always taxi with it leaned as far

>> as the engine with still run smoothly.  I always lean in the air, even

>> at low altitude, when the power is reduced for cruise.  Plugs run pretty

>> clean for 100 hrs.

>> 

>> Cliff

> 

> 

> Thanks for the input, Cliff.  I now taxi lean to peak rpm.  And do lean in the air even at low altitude as long as the power is low.

> 

> Plane gives the 200+ idle rpm increase whether the engine is cold or its been flying for hours.

> 

> Makes sense to do the carb heat check while rich.  Will try the lean mag runup.  Hoping that's the key.

> 

> Thanks again.

> 

> Barry

> 

> 

> 

> 

> Read this topic online here:

> 

> http://forums.matronics.com/viewtopic.php?p=373807#373807

> 

> 

> 

> 

> 

> 

> 

> 

> 

> 

> 

 Well, your idle mixture adjustment is way to rich if you are getting 200+ rpm rise when you lean, if your checking it with a warm engine. You might see that much with a cold engine right after start up.

 

 Turn your idle mixture screw in 1/2 turn and recheck it.

 

 Cliff

bhauskne(at)gmail.com
Guest

Posted: Thu May 24, 2012 9:43 pm Post subject: Plugs leading up worse than normal

And yet the standard procedure we are all taught is 1800 Mag check. Sounds like you are giving unsubstantiated advice that is contrary to aircraft and engine operating instructions. 

Probably better to stick to the aircraft operating manual. On May 24, 2012 10:36 PM, "Gary L Vogt" <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:[quote] --> TeamGrumman-List message posted by: Gary L Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)>

 Most people check the rpm incorrectly.

 At idle, full rich, engine warm, it should idle about 600-650 rpm. Lower is better since it makes landing easier. My plane idles at 450 rpm.

 At idle, very slowly pull the mixture out.  Very slowly. The engine rpm should go up roughly 50 rpm at sea level. At 1500 feet, figure about 25-30 rpm.

 ANY throttle setting other than throttle closed at idle and the carb will NOT be operating on the idle circuit. Any checking of rpm rise without the throttle closed will give an artificially rich indication since the carb is operating on the transition circuit.

 Gary

 Sent from my iPad

 On May 24, 2012, at 2:19 PM, "bkspero" <bkspero(at)gmail.com (bkspero(at)gmail.com)> wrote:

 > --> TeamGrumman-List message posted by: "bkspero" <bkspero(at)gmail.com (bkspero(at)gmail.com)>

 >

 >

 > flyv35b(at)minetfiber.com wrote:

 >>

 >>

 >> First off you can't check the idle mixture unless the engine is fully

 >> warmed up (after flying).  Then you should get about a 25 rpm rise from

 >> full rich when you lean slowly at 800-1000 rpm, say.

 >>

 >> I always check carb heat at full rich mixture and see about 100 rpm drop

 >> at 1700rpm.  I then lean to max rpm and it rises about 50 rpm or

 >> thereabouts.  I let it run there for 10 seconds and then do the mag

 >> check with it leaned.  I leave it leaned until ready to takeoff and then

 >> shove the mixture in.  You won't forget as the engine will stumble upon

 >> throttle application if you forget.  I always taxi with it leaned as far

 >> as the engine with still run smoothly.  I always lean in the air, even

 >> at low altitude, when the power is reduced for cruise.  Plugs run pretty

 >> clean for 100 hrs.

 >>

 >> Cliff

 >

 >

 > Thanks for the input, Cliff.  I now taxi lean to peak rpm.  And do lean in the air even at low altitude as long as the power is low.

 >

 > Plane gives the 200+ idle rpm increase whether the engine is cold or its been flying for hours.

 >

 > Makes sense to do the carb heat check while rich.  Will try the lean mag runup.  Hoping that's the key.

 >

 > Thanks again.

 >

 > Barry

 >

 >

 >

 >

 > Read this topic online here:

 >

 > http://forums.matronics.com/viewtopic.php?p=373807#373807

 >

 >

 >

 >

 >

 >

 >

 >

 >

 >

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 http://forums.matronics.com

 ===========

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

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 [b]

teamgrumman(at)yahoo.com
Guest

Posted: Thu May 24, 2012 10:04 pm Post subject: Plugs leading up worse than normal

Brian H, 



Maybe you have trouble understanding the written English. We are not talking about mag checks. I was not giving unsubstantiated advice.



I am describing setting the engine idle and idle mixture. 



If you are having trouble following the conversation, I suggest you reread the text. If you are still having trouble following the conversation, go have another beer and reread it in the morning. 



Gary

Sent from my iPad



On May 24, 2012, at 10:41 PM, Brian Hausknecht <bhauskne(at)gmail.com> wrote:



[quote] And yet the standard procedure we are all taught is 1800 Mag check. Sounds like you are giving unsubstantiated advice that is contrary to aircraft and engine operating instructions.

 

 Probably better to stick to the aircraft operating manual.

 

 On May 24, 2012 10:36 PM, "Gary L Vogt" <teamgrumman(at)yahoo.com> wrote:

 

 

 Most people check the rpm incorrectly.

 

 At idle, full rich, engine warm, it should idle about 600-650 rpm. Lower is better since it makes landing easier. My plane idles at 450 rpm.

 

 At idle, very slowly pull the mixture out.  Very slowly. The engine rpm should go up roughly 50 rpm at sea level. At 1500 feet, figure about 25-30 rpm

bhauskne(at)gmail.com
Guest

Posted: Thu May 24, 2012 10:20 pm Post subject: Plugs leading up worse than normal

Nope, didn't misunderstand English.  Reread the discussion and you will see that it includes the mag check process, which is the process we typically do to check the mags which also includes leaning for the rpm increase. I see now that you were talking about a different test that is not normally done, a mixture check at idle.  Not in any of my checklists but I see now that this could be another useful check of idle mixture. Probably something my AI does at annual.  

Sorry for suggesting you were looking at a process different than our manuals, you were adding another check. On May 24, 2012 11:06 PM, "Gary L Vogt" <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:[quote] Brian H, 

Maybe you have trouble understanding the written English. We are not talking about mag checks. I was not giving unsubstantiated advice.

 I am describing setting the engine idle and idle mixture. 

If you are having trouble following the conversation, I suggest you reread the text. If you are still having trouble following the conversation, go have another beer and reread it in the morning. 

Gary

Sent from my iPad

On May 24, 2012, at 10:41 PM, Brian Hausknecht <bhauskne(at)gmail.com (bhauskne(at)gmail.com)> wrote:

 	  Quote: 	

And yet the standard procedure we are all taught is 1800 Mag check. Sounds like you are giving unsubstantiated advice that is contrary to aircraft and engine operating instructions. 

Probably better to stick to the aircraft operating manual. On May 24, 2012 10:36 PM, "Gary L Vogt" <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote: 	  Quote: 	
		    --> TeamGrumman-List message posted by: Gary L Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)>

 Most people check the rpm incorrectly.

 At idle, full rich, engine warm, it should idle about 600-650 rpm. Lower is better since it makes landing easier. My plane idles at 450 rpm.

 At idle, very slowly pull the mixture out.  Very slowly. The engine rpm should go up roughly 50 rpm at sea level. At 1500 feet, figure about 25-30 rpm.

 ANY throttle setting other than throttle closed at idle and the carb will NOT be operating on the idle circuit. Any checking of rpm rise without the throttle closed will give an artificially rich indication since the carb is operating on the transition circuit.

 Gary

 Sent from my iPad

 On May 24, 2012, at 2:19 PM, "bkspero" <bkspero(at)gmail.com (bkspero(at)gmail.com)> wrote:

 > --> TeamGrumman-List message posted by: "bkspero" <bkspero(at)gmail.com (bkspero(at)gmail.com)>

 >

 >

 > flyv35b(at)minetfiber.com wrote:

 >>

 >>

 >> First off you can't check the idle mixture unless the engine is fully

 >> warmed up (after flying).  Then you should get about a 25 rpm rise from

 >> full rich when you lean slowly at 800-1000 rpm, say.

 >>

 >> I always check carb heat at full rich mixture and see about 100 rpm drop

 >> at 1700rpm.  I then lean to max rpm and it rises about 50 rpm or

 >> thereabouts.  I let it run there for 10 seconds and then do the mag

 >> check with it leaned.  I leave it leaned until ready to takeoff and then

 >> shove the mixture in.  You won't forget as the engine will stumble upon

 >> throttle application if you forget.  I always taxi with it leaned as far

 >> as the engine with still run smoothly.  I always lean in the air, even

 >> at low altitude, when the power is reduced for cruise.  Plugs run pretty

 >> clean for 100 hrs.

 >>

 >> Cliff

 >

 >

 > Thanks for the input, Cliff.  I now taxi lean to peak rpm.  And do lean in the air even at low altitude as long as the power is low.

 >

 > Plane gives the 200+ idle rpm increase whether the engine is cold or its been flying for hours.

 >

 > Makes sense to do the carb heat check while rich.  Will try the lean mag runup.  Hoping that's the key.

 >

 > Thanks again.

 >

 > Barry

 >

 >

 >

 >

 > Read this topic online here:

 >

 > http://forums.matronics.com/viewtopic.php?p=373807#373807

 >

 >

 >

 >

 >

 >

 >

 >

 >

 >

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Posted: Thu May 24, 2012 10:20 pm Post subject: Plugs leading up worse than normal

As for rpm drop during carb heat teat, I check at 1800 rpm leaned. It's in my checklist right after mag check. 

 I have records of over 2000 post annual checks for engine runup. On the average, carb heat decreases rpm anywhere from 50 to 100 rpm. It makes a difference what the OAT is, it makes a difference what the altimeter setting is. The same plane will show various rpm drops as the annual cycles months over the years. 

During the carb heat rise testing for the Jaguar cowling, I tested two different Tiger air boxes. The early ones (pre-77) give less rpm drop. The air isn't as hot. Lots of leaks. 

Gary

Sent from my iPad

On May 24, 2012, at 11:03 PM, Gary L Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:

[quote]Brian H, 

Maybe you have trouble understanding the written English. We are not talking about mag checks. I was not giving unsubstantiated advice.

I am describing setting the engine idle and idle mixture. 

If you are having trouble following the conversation, I suggest you reread the text. If you are still having trouble following the conversation, go have another beer and reread it in the morning. 

Gary

Sent from my iPad

On May 24, 2012, at 10:41 PM, Brian Hausknecht <bhauskne(at)gmail.com (bhauskne(at)gmail.com)> wrote:

 	  Quote: 	

And yet the standard procedure we are all taught is 1800 Mag check. Sounds like you are giving unsubstantiated advice that is contrary to aircraft and engine operating instructions. 

Probably better to stick to the aircraft operating manual. On May 24, 2012 10:36 PM, "Gary L Vogt" <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote: 	  Quote: 	
		   --> TeamGrumman-List message posted by: Gary L Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)>

 Most people check the rpm incorrectly.

 At idle, full rich, engine warm, it should idle about 600-650 rpm. Lower is better since it makes landing easier. My plane idles at 450 rpm.

 At idle, very slowly pull the mixture out.  Very slowly. The engine rpm should go up roughly 50 rpm at sea level. At 1500 feet, figure about 25-30 rpm.

 ANY throttle setting other than throttle closed at idle and the carb will NOT be operating on the idle circuit. Any checking of rpm rise without the throttle closed will give an artificially rich indication since the carb is operating on the transition circuit.

 Gary

 Sent from my iPad

 On May 24, 2012, at 2:19 PM, "bkspero" <bkspero(at)gmail.com (bkspero(at)gmail.com)> wrote:

 > --> TeamGrumman-List message posted by: "bkspero" <bkspero(at)gmail.com (bkspero(at)gmail.com)>

 >

 >

 > flyv35b(at)minetfiber.com wrote:

 >>

 >>

 >> First off you can't check the idle mixture unless the engine is fully

 >> warmed up (after flying).  Then you should get about a 25 rpm rise from

 >> full rich when you lean slowly at 800-1000 rpm, say.

 >>

 >> I always check carb heat at full rich mixture and see about 100 rpm drop

 >> at 1700rpm.  I then lean to max rpm and it rises about 50 rpm or

 >> thereabouts.  I let it run there for 10 seconds and then do the mag

 >> check with it leaned.  I leave it leaned until ready to takeoff and then

 >> shove the mixture in.  You won't forget as the engine will stumble upon

 >> throttle application if you forget.  I always taxi with it leaned as far

 >> as the engine with still run smoothly.  I always lean in the air, even

 >> at low altitude, when the power is reduced for cruise.  Plugs run pretty

 >> clean for 100 hrs.

 >>

 >> Cliff

 >

 >

 > Thanks for the input, Cliff.  I now taxi lean to peak rpm.  And do lean in the air even at low altitude as long as the power is low.

 >

 > Plane gives the 200+ idle rpm increase whether the engine is cold or its been flying for hours.

 >

 > Makes sense to do the carb heat check while rich.  Will try the lean mag runup.  Hoping that's the key.

 >

 > Thanks again.

 >

 > Barry

 >

 >

 >

 >

 > Read this topic online here:

 >

 > http://forums.matronics.com/viewtopic.php?p=373807#373807

 >

 >

 >

 >

 >

 >

 >

 >

 >

 >

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Posted: Fri May 25, 2012 4:52 am Post subject: Plugs leading up worse than normal

On 5/24/2012 10:33 PM, Gary L Vogt wrote:

 	  Quote: 	
		   


	


 	  Quote: 	
		   ANY throttle setting other than throttle closed at idle and the carb will NOT be operating on the idle circuit. Any checking of rpm rise without the throttle closed will give an artificially rich indication since the carb is operating on the transition circuit.



 Gary

 Sent from my iPad


	


Where is that documented?  I think the idle circuit goes much higher 

than 650 rpm as I found out in the middle of Australia when flying a 

Tiger which had the idle circuit completely blocked with debris!



Cliff

bkspero

Joined: 23 May 2012
Posts: 17

Posted: Fri May 25, 2012 7:34 am Post subject: Re: Plugs leading up worse than normal

 	  teamgrumman(at)yahoo.com wrote: 	
		  If I set the plugs, I set them to .018. 



Gary

Sent from my iPad



On May 24, 2012, at 2:10 PM, "bkspero" <bkspero> wrote:



	




No, these were installed by the other A&P that Alan tried.



I will check the mixture as you described.  Most of my hot adjustments of the mixture were during taxi where the throttle was set a little higher than idle.  Sounds like that could explain why I am seeing >50 rpm increase on leaning even hot.



Won't get to any of this stuff unless the weather here gets better though.  Maybe tomorrow.



Thanks again, all.



Barry S(2)

teamgrumman(at)yahoo.com
Guest

Posted: Fri May 25, 2012 11:59 am Post subject: Plugs leading up worse than normal

If the idle circuit is completely blocked with debris, as you say, then the engine is operating on the transition or main circuits.  You can completely close the mixture down and still make the engine run.  That tells you nothing.  You can even MAKE the engine idle with no flow from the idle circuit.  It will run on the rest of the carb.

There are three fuel delivery circuits in a carb.  IDLE, Transition, and Main.

IDLE:  No fuel flow through the main venturi.  No flow through the main jet(s).   All of the fuel flow comes from the idle circuit in the carb.  There is no jet which changes the amount of fuel delivered.  Fuel flow is adjusted by the IDLE mixture screw.  The IDLE  fuel delivery comes from a metered slot in the carb.  

Transition: This is nothing more than an additional slot (or, sometimes, additional fuel to the IDLE slot) as the throttle plate opens.  As the throttle plate opens further, manifold vacuum causes fuel to flow from the transition slot.  This is to cover up a lean condition as the throttle plate is opened and the IDLE circuit cannot supply enough fuel.  

Main:  At some throttle plate position beyond transition, where the main venturi begins to flow fuel, the air-fuel mixture ratio is set by the main jet and the main venturi deliver system.  

===============

I have a customer, who shall remain anonymous, who insists his mixture is too rich because he gets a 200 rpm rise when leaning at 1800 rpm from  full rich.  He'll go home and fuck with the idle mixture crew after every annual.  And, every annual I have to reset the IDLE.  

        From: flyv35b <flyv35b(at)minetfiber.com>

 To: teamgrumman-list(at)matronics.com 

 Sent: Friday, May 25, 2012 5:52 AM

 Subject: Re: TeamGrumman-List: Re: Plugs leading up worse than normal

  

 

 --> TeamGrumman-List message posted by: flyv35b <flyv35b(at)minetfiber.com (flyv35b(at)minetfiber.com)>



On 5/24/2012 10:33 PM, Gary L Vogt wrote:

 	  Quote: 	
		   -->  TeamGrumman-List message posted by: Gary L Vogt<teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)>


	


 	  Quote: 	
		   ANY throttle setting other than throttle closed at idle and the carb will NOT be operating on the idle circuit. Any checking of rpm rise without the throttle closed will give an artificially rich indication since the carb is operating on the transition circuit.

 

 Gary

 Sent from my iPad


	


Where is that documented?  I think the idle circuit goes much higher than 650 rpm as I found out in the middle of Australia when flying a Tiger which had the idle circuit completely blocked with or?TeamGrumman-List" target="_blank">http://www.matronics.com/Navigator?T               - MATRONICS WEB FORUMS -

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