Cleaning Spark Plugs is a Simple Job...

Jay,
If you have a shield around the exhaust check for dirt, sand and small
rocks. This will sound like the car is falling apart.
Michelle

Jay Honeck wrote:

Oh my God, the prop!!



Funny you should mention that. It could, actually, *be* the prop -- but to
my ear it sounds more like a very slight engine roughness rather than a prop
imbalance.

Sometimes it's hard to separate the two -- and sounds have a funny way of
traveling.

For example, our Subaru Outback has developed a very annoying rattle in the
right rear that starts at around 50 mph. It's a harmonic rattle, and we've
looked at EVERYTHING trying to find something loose, to no avail. Yet,
clearly, there is something very loose, somewhere. Our best guess at this
point is that it's something inside the right rear door -- but I haven't had
time to rip it apart to see.

When you finished, did you "properly" store the torque wrench?
(Just a test to see if you read the instructions that came with the
tool.)

Um, well, I very carefully put it back in the cheap plastic case it came in,
and wrapped the directions around the handle.
Was there more to it?

You are supposed to release the setting/set it to zero/whatever it is
called, to take the pressure/stress/strain/whatever off the torque break
mechanism.

George Patterson wrote:
Margy wrote:

I always find my mechanic is pleased when after using her tools I
sweep the hangar, go buy lunch, bring the sodas, etc.


And I just find that my mechanic gets ****ed when I use his tools. :-)

Not everyone is allowed to use her tools and you know which ones you can
and can't and if one asks, puts away and cleans up they get to use them
again.

Margy

George Patterson
Give a person a fish and you feed him for a day; teach a person to
use the Internet and he won't bother you for weeks.

Releasing the tension on the torque wrench's spring maintains its
accuracy, but most torque wrenches aren't very accurate when new,
especially cheap imported ones. Standard practice as per AC43.13 (and
required by aircraft maintenance law, at least in Canada) is to have it
calibrated when new, and then every year or two depending on use. It
can cost more to calibrate the thing than it cost to buy it, which is
why they're so inaccurate when boxed at the factory.

Dan

Talk to your A&P. Proceedure is specified in the Service Bulletin.
Mag(s) have to be removed, split, internally inspected (particularly
the impulse coupling), lubricated, both the E gap and points gap set,
new gaskets, reinstalled on the engine, and retimed.

The E-gap is determined by points gap; they're not separate
settings. The ideal is to set the E-gap, since wear to the points and
cam can result in the wrong E-gap if the adjustment is made using
points gap.
Most of my students struggle with the theory of the magneto's
operation, and I imagine most pilots are no better off. The E-gap is
the point at which the mag's rotor (a strong permanent magnet) is past
the neutral point after having generated a current in the primary
winding. This current generates its own field, which in beginning to
collapse tends to maintain current flow in the winding after the rotor
has passed through neutral and stopped generating. To get spark, we
open the points when the maximum magnetic flux change will happen, and
when the points open the current is arrested suddenly, the field
collapses violently, generating a large voltage in the secondary
winding. Big spark for the plug.
If the E-gap is off, the spark's strength is reduced and
roughness may occur.

Mag that are slightly mistimed can cause roughness, too. If the
engine's data plate calls for them to be set at the same TDC angle, you
want them real close to being together. If one is much later than the
other. the pressure rise in the cylinder caused by the first plug's
firing can get high enough to prevent the second plug's firing, and the
cylinder loses a bit of power. Sparkplugs need more voltage than mags
can provide to spark at high pressures.
Worn points cause resistance that prevents full current flow in
the primary winding. A worn capacitor can leak and reduce spark
intensity. An open capacitor can kill spark altogether, and one will
reduced capacity will burn the points. The Slick distributor's rotor
bushings wear and the rotor's finger gap can get too big and weaken
spark. Lots of reasons to open the mags and spend a bit of money on
them.
We've recently had trouble with AC plugs; the internal resistor
seems to be failing. Champs have had that problem for years.

Dan

If you have a shield around the exhaust check for dirt, sand and small
rocks. This will sound like the car is falling apart.

Thanks, Michelle -- but I just found the source of the rattle ten minutes
ago. I took the right rear door apart, and the retaining screws for the
stereo speaker had simply vibrated out over the last 8 years. The speaker
was just laying loose inside the door...

And to think I laid under the car for 30 minutes trying to find loose
stuff... Argh.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Lots of reasons to open the mags and spend a bit of money on
them.

Much good stuff snipped

Wow -- thanks, Dan. I didn't understand half of what you wrote, but I've
saved your post for the future day when I've got time to figure out things
like "electricity" and "engines"...

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"
wrote in message
oups.com...
Talk to your A&P. Proceedure is specified in the Service Bulletin.
Mag(s) have to be removed, split, internally inspected (particularly
the impulse coupling), lubricated, both the E gap and points gap set,
new gaskets, reinstalled on the engine, and retimed.

The E-gap is determined by points gap; they're not separate
settings. The ideal is to set the E-gap, since wear to the points and
cam can result in the wrong E-gap if the adjustment is made using
points gap.
Most of my students struggle with the theory of the magneto's
operation, and I imagine most pilots are no better off. The E-gap is
the point at which the mag's rotor (a strong permanent magnet) is past
the neutral point after having generated a current in the primary
winding. This current generates its own field, which in beginning to
collapse tends to maintain current flow in the winding after the rotor
has passed through neutral and stopped generating. To get spark, we
open the points when the maximum magnetic flux change will happen, and
when the points open the current is arrested suddenly, the field
collapses violently, generating a large voltage in the secondary
winding. Big spark for the plug.
If the E-gap is off, the spark's strength is reduced and
roughness may occur.

Mag that are slightly mistimed can cause roughness, too. If the
engine's data plate calls for them to be set at the same TDC angle, you
want them real close to being together. If one is much later than the
other. the pressure rise in the cylinder caused by the first plug's
firing can get high enough to prevent the second plug's firing, and the
cylinder loses a bit of power. Sparkplugs need more voltage than mags
can provide to spark at high pressures.
Worn points cause resistance that prevents full current flow in
the primary winding. A worn capacitor can leak and reduce spark
intensity. An open capacitor can kill spark altogether, and one will
reduced capacity will burn the points. The Slick distributor's rotor
bushings wear and the rotor's finger gap can get too big and weaken
We've recently had trouble with AC plugs; the internal resistor
seems to be failing. Champs have had that problem for years.

Dan

Jay Honeck wrote:
Why, because I *knew* it would **** you off, Jay!
:-)

Nah.

Seriously, we're not all experts here. I write like things like that
because when I was a new owner, I learned from other posters who wrote stuff
like that here.

It's a good idea, but if you really look at your post, you're not really
teaching anyone anything. You mostly said "my mechanic showed me how
to...", etc. I think that cleaning/gapping sparkplugs is probably one of
those things that someone needs to *see*. If we're gonna teach the
newsgroup newbies, we should probably document how to do it with digital
pictures and post them somewhere.

--- Jay


--
__!__
Jay and Teresa Masino ___(_)___
http://www2.ari.net/jmasino ! ! !
http://www.OceanCityAirport.com
http://www.oc-Adolfos.com

It's a good idea, but if you really look at your post, you're not really
teaching anyone anything.

He's teaching much. A lot of other pilots might think cleaning
and gapping plugs is a simple thing, and Jay's detailing of his
experience showed that it's not. Reading his post saves them fumbling
through the same process if they realize they're not going to enjoy it,
and might save them money if it keeps them from damaging plugs or
stripping plug threads out of the cylinder head.

Dan

wrote:
Releasing the which is
why they're so inaccurate when boxed at the factory.

Dan

Which is why I prefer bending beam type torque wrenches. At least the
stiffness of steel won't change with time. If it returns to zero, it
should be OK to use again. With the detent/click type, you never know,
although I don't see where returning them to zero will reduce any
internal plastic deformation. Steel doesn't creep at normal
temperatures.


One minor additional thing - Occasionally also clean the sparkplug
helicoil threads in the cylinder. Somewhere (a surplus tore as I
recall) I found some small wire brushes about 3/8 inch dia that could
be chucked into an electric drill and slowly rotated in the threaded
hole to clean the crud out of the threads.