[f-AA] Leaning Continental C85 engine

[Sam Burke]

I need some advise regarding leaning during taxi. I need to taxi about a mile to the active runway at SMX and so I set the mixture control on lean during the one mile taxi. So far I have not had any plug fouling detected during run up. Can I do any damage to the valves by doing this? Some friends have told me that the mixture control on Continental engines does nothing.

Regards,
Sam Red Flicker N6404C 1947 L16A C85-12 engine
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[Rich Dugger Gmail]

Depending on which carb you have it doesn't do much.
Why not burn car gas with no lead then it isn't an issue.
You can't foul it with lead if there is no lead...

Rich

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Subject: [f-AA] Leaning Continental C85 engine

> I need some advise regarding leaning during taxi. I need to taxi about a
> mile to the active runway at SMX and so I set the mixture control on lean
> during the one mile taxi. So far I have not had any plug fouling detected
> during run up. Can I do any damage to the valves by doing this? Some
> friends have told me that the mixture control on Continental engines does
> nothing.
>

_______________________________________________

[Ian Harvie]

Sam, if you have the Stromberg it will not stop the engine when pulled
full lean, It is not an idle cut off but controls the air allowed into
the float chamber which effectively alters the mixture . If you had a
Marvel Schebler pulling full lean will stop the engine. Either way
taxing with a lean mixture will not cause problems particularly as you
have such a low power setting.
What altitude are you? I once operated out of an airfield about 5500
feet and you adjusted mixture lean for take off to achieve full power.
As Rich says, use mogas, but make sure it has no ethanol.
I haven't fouled a plug in the last 100 hours, and never pulled them to
clean them.

Ian

[Tom Holmes]

If you have a Stromberg, leaning only happens about 1700 rpm.  If you have a Marvel Shebler, it works like any other carburetor.  I don't think you can hurt your engine on the ground in that period of time. Tom --- On Mon, 12/27/10, Rich Dugger Gmail <richd...@gmail.com> wrote:

[Cy Galley]

First, Car gas is illegal if your don't have the STC. Second, if the car
gas has any alcohol, you have problems... It is corrosive, and alcohol is
the solvent for many of the assembly sealers such as Pematex and Titeseal.

Cy Galley; Editor - Aeronca Aviator
Supporting Aeroncas every day
www.aeronca.org

[richd...@gmail.com]

Well, of course it's illegal w/out an STC. And no, you don't want alcohol. I assumed everybody knows that. Having said that...
Get the STC, test for alcohol and avoid all the crappy problems with the fouling of the plugs and putting the lead into the air. It is a win win.
Oh, BTW it is about 2-3 dollars a gallon cheaper to buy. At 5 GPH that will save you 10 - 15 bucks an hour.
I am trying to find a downside...
Rich
Remember: Always finish what you sta

[Sam Burke]

The carburetor on my C85-12 is a Stromberg NAS3A1

Sam Red Flicker N6404C L16A

[ginny wilken]

If you are at anything 65% power or less, there is no way to generate intracylinder pressures that will hurt anything. This is how running lean-of-peak works. You can run as lean as you want until it just shuts off. I am in the habit of leaning for taxi, as well as in cruise.

ginny

On Dec 27, 2010, at 6:12 AM, Tom Holmes wrote:

All stunts performed without a net!

[Vand...@aol.com]

Sam

And how many hours on the engine?  I ask because one of the signs of an aging engine is excessive oil consumption.  Running the engine at 1200 rpm (a little hotter) on the ground and leaning during long taxi runs will reduce the likelihood of fouling plugs on the ground and the resultant "bad mag" check. 

I did note that you said that you didn't have the fouling problem and I offer this info just in case.

Good luck,

Dan vdMeer

 

In a message dated 12/27/2010 12:05:13 P.M. Eastern Standard Time, samb...@verizon.net writes:

The carburetor on my C85-12 is a Stromberg NAS3A1

Sam Red Flicker N6404C L16A

[Sam Burke]

Dan,

I have 630 hours on my C85-12. I did experience mag drops of as much as 150 rpm (lower plugs) before I did lean on taxi.

Sam N6404C 1947 L16a

[Vand...@aol.com]

Sounds like oil fouling.  I'd keep it as lean as possible on the ground and

[Vand...@aol.com]

Sounds like oil fouling.  I'd keep it as lean as possible on the ground and in the air and keep the rpms up a bit on the ground.  The normal heating from the engine in flight will keep the plugs clean of oil.

Short mag checks, no more that 2-3 seconds are also a good idea on the ground.  And Tony Markl suggested to me that a quick mag check periodically in flight, particularly on cross country trips is not a bad idea.

Dan

[John Rodkey]

He can't burn car gas, because he lives in California, and all the fuel here has ethanol in it.

On Sun, Dec 26, 2010 at 9:31 PM, Rich Dugger Gmail <richd...@gmail.com> wrote:

Depending on which carb you have it doesn't do  much.
Why not burn car gas with no lead then it isn't an issue.
You can't foul it with lead if there is no lead...


Rich

--
John (poobah) Rodkey - N9361E 11AC at Goleta