Massive Spark Plugs Help

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DatDudeMIC
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Massive Spark Plugs Help

Post by DatDudeMIC »

Can someone please explain how to properly use the massive spark plugs. Everytime I taxi, they always seem to foul by the time I'm ready to do a run-up. I lean while I'm on the ground and keep the throttle at least 1100 RPM and they still seem to foul. Am I doing something wrong or missing a step or two??

Thanks in advance
Keep The Blue Side Up,

Micah H.

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LZ-WIL
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Re: Massive Spark Plugs Help

Post by LZ-WIL »

Hello,

It depends on how much you lean and what rpm you keep on the ramp and during taxi. When I start my C172 (for example) after the oil pressure stabilizes, I set rpm to 1200 then lean until rpm starts to drop and return 2 notches of the mixture lever, then I lower the rpm to a 900 rpm. When engine
warms a bit it slowly rises to 1000 rpm. My usual mixture lean is between 52-57% mixture (it depends on what elevation is the airport). I taxi between 900-1000 rpm, since C172 gains up speed pretty good with 1000 rpm on a concrete or asphalt taxiway - too much some times. :wink:

Cheerz,
Will
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Nick - A2A
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Re: Massive Spark Plugs Help

Post by Nick - A2A »

Yeah, the key is what's generally referred to as aggressive leaning. This recent video by Rod Machado explains the idea behind it and also the safety benefit of leaning the mixture in this way.


Nice colour scheme Rod!

That being said, I have sometimes wondered if the propensity for A2A's massive spark plugs to foul very quickly is a little exaggerated, for dramatic effect, so to speak. :mrgreen:

Cheers,
Nick

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Lewis - A2A
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Re: Massive Spark Plugs Help

Post by Lewis - A2A »

To come at this at a different angle;

If you are checking the hangar regulary then all I can say is stop as that might be your issue right there. Fouled plugs to varying degress will happen, and you wont always know about. So if you get out the habit of using the hangar to check unless you really notice something that'll help you massively.

thanks,
Lewis
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Scott - A2A
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Re: Massive Spark Plugs Help

Post by Scott - A2A »

Fine wire plugs will eliminate any fouling.

If instead you want to use massive plugs, you will need to keep your idle up closer to 1000rpm. This has more effect than leaning, as leaning on the ground except towards the absolute edge of the stall does little to nothing.

While many airplane engines can idle lower than 1000rpm with massive plugs without fouling, there is a fair amount that can't, and since we offer two types of plugs, we chose to model those airplanes in the fleets around the world that do require "anti fouling procedures" to be used.

Scott.
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gege21
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Re: Massive Spark Plugs Help

Post by gege21 »

Hello and thanks for the replies,

I get also most of the time spark plugs fouled (using massive plugs) even leaning agressive to 45%/37% on the ground and taxiing under standard temperatures at an elevation airport of 726 feets.

As when the engine is cold it is mentioned in the manual to don't set above 1000 rpm and on another page it is advertised to run at 1200 rpm and lean the mixture to lower the rpm to 1000 rpm or less (may be 850/950 rpm will be a reasonnable range). While running at 1200 rpm and leaning to set 950 rpm, I get always spark plugs fouled.
May be retrieving the additive oil could get ride of this very difficult thing to be away from fouled plugs but I don't know.

I love to try to manage well on the run up to clear the fouled spark plugs as explained on the A2A YouTube C172 video part 2 but have serious difficulty to clear the fouled plugs; I must have to retry more one time the process to be cleared from fouled. And sometimes I must return to the hangar to clear the plugs.

I believed that the fuel 100LL for aviation was much filtered than the one for a normal car and thus was cleaner from impurities.

Cheers
Gerard
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AKar
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Re: Massive Spark Plugs Help

Post by AKar »

Nicely done by Machado in bringing attention to this common fuel enrichment feature that is activated near full throttle. This is something that is not brought up too often. If anything, it should answer the question if one should do reduced power takeoffs, or slight climb power reductions, in piston airplanes: don't!!!

-Esa

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gege21
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Re: Massive Spark Plugs Help

Post by gege21 »

Hello,

Sometime ago I discovered this very interesting video well commented and explained (thanks to his author):

https://www.youtube.com/watch?v=_VfiPuheeGw

Cheers
Gerard
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bobsk8
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Re: Massive Spark Plugs Help

Post by bobsk8 »

On 152's I used to fly, I would lean while taxiing until the engine was barely running, to keep the plugs from lead fouling. Once in awhile, lean a tad to much, and the engine would quit. Passengers used to get a bit worried when that happened, until I explained what I was doing.
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gege21
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Re: Massive Spark Plugs Help

Post by gege21 »

bobsk8 wrote:On 152's I used to fly, I would lean while taxiing until the engine was barely running, to keep the plugs from lead fouling. Once in awhile, lean a tad to much, and the engine would quit. Passengers used to get a bit worried when that happened, until I explained what I was doing.
"Engine was barely running" does it mean to hear the engine become rough just before loosing too much RPM ? As I could constat at this rough sound engine run I must add a little bit more mixture to get sufficient power to be able to move at 950/1000 RPM. In the sim I am able to lean the mixture to about 37% and the throttle at the same value or a tiny less at 35% and all goes fine without to have so much fouled plugs during taxiing (My airport is at 726 feet Alt. with standard temperature at 13/14 ° C depending of the season).

And yes engine quitting during taxiing is doing a bad impression to the passengers. What happen next ?

Cheers
Gerard
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bobsk8
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Re: Massive Spark Plugs Help

Post by bobsk8 »

gege21 wrote:
bobsk8 wrote:On 152's I used to fly, I would lean while taxiing until the engine was barely running, to keep the plugs from lead fouling. Once in awhile, lean a tad to much, and the engine would quit. Passengers used to get a bit worried when that happened, until I explained what I was doing.
"Engine was barely running" does it mean to hear the engine become rough just before loosing too much RPM ? As I could constat at this rough sound engine run I must add a little bit more mixture to get sufficient power to be able to move at 950/1000 RPM. In the sim I am able to lean the mixture to about 37% and the throttle at the same value or a tiny less at 35% and all goes fine without to have so much fouled plugs during taxiing (My airport is at 726 feet Alt. with standard temperature at 13/14 ° C depending of the season).

And yes engine quitting during taxiing is doing a bad impression to the passengers. What happen next ?

Cheers
Gerard
Running rough but not stalling, was my rule. I only took off once and had to return to the airport, because of a lead fouled plug causing rough operation that I could not cure in the air. If the engine stopped while taxiing, I just cranked it up again and continued. Only happened twice in years of flying.
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gege21
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Re: Massive Spark Plugs Help

Post by gege21 »

Hello felow fan flyers,

I would like to come back to this spark plugs massive fouled. When starting the engine in normal procedure and normal weather temp, as soon as the engine is started I push the mixture lever to full rich (the throttle is still on "cracked" position), then I push a bit the throttle lever just to set the 1000 rpm and I pull back the mixture to about 31/32 percent of his course lever and to avoid to stall the engine I push the throttle lever a bit more to about 80 percent of the course lever; now the engine rpm is idling and waving between 700 to 950/1000 rpm. Is it a normal idling when the engine rpm rod on the rpm tachometer waving between 700 and 950/1000 rpm all the time when stand still and even when taxiing before takeoff ? With this engine setup (mixture+throttle sets) if I want to move from stand still, I push the throttle lever to max (100 %) to be able to move on and the engine rpm is still waving between 700 and 1000 rpm but the engine don't run rough. I think a mixture lever set at 30/32 % is an agressive leaning set. But what I wish to know is : engine rpm waving al the time during taxiing is there a normal or acceptable behavior for a smooth engine run ? In the same time to avoid fouling spark plugs this agressive leaning mixture works pretty well for me at the least.

Cheers
Gérard
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bobsk8
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Re: Massive Spark Plugs Help

Post by bobsk8 »

gege21 wrote: 26 Jan 2020, 11:24 Hello felow fan flyers,

I would like to come back to this spark plugs massive fouled. When starting the engine in normal procedure and normal weather temp, as soon as the engine is started I push the mixture lever to full rich (the throttle is still on "cracked" position), then I push a bit the throttle lever just to set the 1000 rpm and I pull back the mixture to about 31/32 percent of his course lever and to avoid to stall the engine I push the throttle lever a bit more to about 80 percent of the course lever; now the engine rpm is idling and waving between 700 to 950/1000 rpm. Is it a normal idling when the engine rpm rod on the rpm tachometer waving between 700 and 950/1000 rpm all the time when stand still and even when taxiing before takeoff ? With this engine setup (mixture+throttle sets) if I want to move from stand still, I push the throttle lever to max (100 %) to be able to move on and the engine rpm is still waving between 700 and 1000 rpm but the engine don't run rough. I think a mixture lever set at 30/32 % is an agressive leaning set. But what I wish to know is : engine rpm waving al the time during taxiing is there a normal or acceptable behavior for a smooth engine run ? In the same time to avoid fouling spark plugs this agressive leaning mixture works pretty well for me at the least.

Cheers
Gérard
Sounds like you are too lean to me. I would advance the mixture until the idle just smooths out.
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gege21
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Re: Massive Spark Plugs Help

Post by gege21 »

Yes I probably lean too much but if I follow the Scott's advice to set the 1000 rpm by adjusting the mixture and throttle, I get always fouled spark plugs when the run up come because my taxi way is a bit long to run at the active runway; if I understand you are meaning is to set the rpm at a steady 1000 rpm by adjusting the throttle and mixture, but to don't get a waving rpm as I had set mine ?! A steady 1000 rpm is preferable to a waving rpm right ?

PS: I tried the two methods waving rpm between 700 and 1000 rpm and what Scott adviced to set a steady 1000 rpm adjusting the throttle and mixture; I do say the Scott method is well to get ride of spark plug fouling as well. But when taxiing with 1000 rpm we reach easily a speed of 20 Kias which is too much for taxiing; I believed a speed to a walk by foot is the regular speed to run on taxiway but I could be wrong so 17/20 Kias are too much. Correct me if I'm wrong please. When running at 1000 rpm I do use much more brakes so often to keep a reasonable speed on the ground.

Over

Cheers
Gérard
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