Color of spark plugs

We just did the annual on our 1945 Aeronca Champ.
Took the plugs out to do the compression test.
On inspecting them, noted that they were black, sootie.
The AI said that is normal for autogas in a Champ.

Honeck always says his plugs are clean when he runs autogas.
Is this the difference beween having a low compression, low horsepower,
no-mixture control engine and having a high compression, high
horsepower, mixture controlled engine?

john smith wrote:

Is this the difference beween having a low compression, low horsepower,
no-mixture control engine and having a high compression, high
horsepower, mixture controlled engine?

Sooty plugs indicate either a too-rich mixture or oil burning. I would say it's
the result of having no mixture control in this case.

George Patterson
A diplomat is a person who can tell you to go to hell in such a way that
you look forward to the trip.

G.R. Patterson III wrote:

john smith wrote:

Is this the difference beween having a low compression, low horsepower,
no-mixture control engine and having a high compression, high
horsepower, mixture controlled engine?


Sooty plugs indicate either a too-rich mixture or oil burning. I would say it's
the result of having no mixture control in this case.

I think it does run rich on the ground, but in cruise at 2150 rpm, I
only burn 3.5 per hour.

"john smith" wrote in message
...
We just did the annual on our 1945 Aeronca Champ.
Took the plugs out to do the compression test.
On inspecting them, noted that they were black, sootie.
The AI said that is normal for autogas in a Champ.

Honeck always says his plugs are clean when he runs autogas.
Is this the difference beween having a low compression, low horsepower,
no-mixture control engine and having a high compression, high
horsepower, mixture controlled engine?

Some of those old Continental A-65 engines have mixture control, most don't.
I fly one that does but the plugs still get dirty. I use a little 100LL
occasionally to help the valves and seats. Try an additive to keep them
from fouling and clear your engine by gently revving it up for a couple of
seconds on the ground and on final. (BTW, I just read in the O-300
Continental manual where it says to "gun" your engine on final to clear it.)
A Marvel-Schebler carburetor has a better mixture control than a Stromberg,
the carb hanging from most A-65's. And most of the Strombergs have been
safety-wired to full rich.

jls wrote:
"john smith" wrote in message
...

We just did the annual on our 1945 Aeronca Champ.
Took the plugs out to do the compression test.
On inspecting them, noted that they were black, sootie.
The AI said that is normal for autogas in a Champ.

Honeck always says his plugs are clean when he runs autogas.
Is this the difference beween having a low compression, low horsepower,
no-mixture control engine and having a high compression, high
horsepower, mixture controlled engine?


Some of those old Continental A-65 engines have mixture control, most don't.
I fly one that does but the plugs still get dirty. I use a little 100LL
occasionally to help the valves and seats. Try an additive to keep them
from fouling and clear your engine by gently revving it up for a couple of
seconds on the ground and on final. (BTW, I just read in the O-300
Continental manual where it says to "gun" your engine on final to clear it.)
A Marvel-Schebler carburetor has a better mixture control than a Stromberg,
the carb hanging from most A-65's. And most of the Strombergs have been
safety-wired to full rich.

We have the Stromberg without the mixture control.
The Bendix carbs with the mixture control are hard to find (lots of
people looking for them). The AI said they don't really do that much for
you on the ground.

OT... He did say that he, too, noticed better performance from 100LL
than from autofuel.He also said that he prefers to fly his Champ with a
mixture of autofuel and 100LL.

On Mon, 01 Mar 2004 13:24:25 GMT, john smith wrote:

snip

We have the Stromberg without the mixture control.
The Bendix carbs with the mixture control are hard to find (lots of
people looking for them). The AI said they don't really do that much for
you on the ground.

The "mixture control" is nothing more than an adjustable bowl vent.
Only flown behind a couple of them, didn't notice any big difference
between the knob being in or out.

I would check the primer pump for leaks, and verify that the seat
height is set correctly. Not sure how much difference it makes, but
with these carbs I've always dummied up the carb install (placing it
at the same height in relation to the fuel in the airplane) to shim
the seat.

I'm assuming that you've already had the Delrin needle/float weight
installed.

Always wanted to drive one with the MS carb on it, never had the
opportunity.

OT... He did say that he, too, noticed better performance from 100LL
than from autofuel.He also said that he prefers to fly his Champ with a
mixture of autofuel and 100LL.

The one I learned to fly in was operated on a mixture of 80, 100LL,
and TCP. Was kinda hard to tell what "color" the plugs were, it tended
to swill engine oil.

TC