Cleaning Spark Plugs is a Simple Job...

On Tue, 27 Sep 2005 02:35:01 GMT, Orval Fairbairn
wrote:


I don't see why you couldn't make a chaser out of an old plug, using a
Moto Tool to cut the tapping slots.

umm errr-that's what I used before one of my employers bought me the
jen-yoo-wine article. Actually, I used a new plug that I had dropped
and subsequently busted the guts out of so somebody else wouldn't try
to stick in in an airplane.

A very important part of Jay's plug-cleaning story was
solvent-cleaning after grit-blasting. Since OSHA didn't spend a lot of
time in the hangar, I allegedly used a highly toxic low-flashpoint
solvent drained out of a nearby sump drain into a cut-down oil bottle.

Had a customer ask me why I was wasting my time (and his money)
rinsing the plugs. Showed him the grit in the bottom of the bottle and
asked him if he really wanted it inside his engine...

TC

wrote:

.... good info snipped...

We've recently had trouble with AC plugs; the internal resistor
seems to be failing. Champs have had that problem for years.

Dan,
I recently used my Fluke 77 DMM to check eight Champion REM40E
spark plugs, which have a built in radio suppression resistor. I
measured Ohms between center electrodes and threads (all Open). I then
measured the resistance through the center electrode from the wire end
to the electrode end, and noticed that two of eight plugs were "Open"
(10MegOhm), while the other six ranged from 1.4K to about 7K.

I expected all of these to be the same resistance, but was surprised at
the variablity plug to plug. I am puzzled at the two that read open.
They were not misfiring before removal. What's going on?

btw- I also measured 12 brand-new RHM40Es; 4 of 12 were open end to
end???

But for the love of Orville, paint the top of the sonofoabitch red or
somebody will try and use it in an airplane as a spark plug. GUARANTEED.

I've got two of them around here. One with a narrow slot for fairly clean
helicoils and one with a Tijuana whore's slot for absolutely filthy
helicoils.

Toecutter's comment about grease in the slot is right on. However, wipe the
helicoil out after you do the cleaning or the grease will stick the next
plug tighter than Tilly's titty.

I switched from the graphite thread lube to the copper loaded stuff and have
found an absolute order of magnitude of ease of removal. Any other
comments?


Jim



"Orval Fairbairn" wrote in message
news
In article ,
wrote:

On 25 Sep 2005 19:26:01 -0700, "nrp" wrote:
Champion useta sell a thread chaser for this purpose. Looked a lot
like a spark plug, had cut-outs in the threads to catch the crud. SOP
was stick a finger full of grease into the cut-outs to help it
"stick".

TC


I don't see why you couldn't make a chaser out of an old plug, using a
Moto Tool to cut the tapping slots.

"mikem" wrote in message
ups.com...
(10MegOhm), while the other six ranged from 1.4K to about 7K.

I expected all of these to be the same resistance, but was surprised at
the variablity plug to plug. I am puzzled at the two that read open.
They were not misfiring before removal. What's going on?

No problem. The ones that read open had a sub-thousandth crack on the
resistor and would arc across the crack before going to the two orders of
magnitude larger crack called a spark gap.



btw- I also measured 12 brand-new RHM40Es; 4 of 12 were open end to
end???

QC strikes again. They only "bomb test" the suckers. If there is a minute
crack between the resistor and the plug, they figure that the plug gap will
predominate in the sparking mechanisms. With the obvious comment that a
spark in oxygen rich atmosphere will wear down a contact MUCH further than
in the combustion chamber. Thus a failed plug in a few hundred hours. I'd
suggest you reject the opens. Unless we all continue to do so, plug
manufacturers will be getting away with this slop.

Jim

We learned a long time ago to bomb-test even brand-new
plugs. We've had new Champs fail right out of the box. It can't be just
a tiny crack in the resistor; there has to be something else going on
here. When I remove that screw inside the barrel and take out the
spring and resistor, I can't find anything wrong with it. And if I take
that stuff out of a working plug, it doesn't want to work again after
reassembly. I think there's something wrong with the spring-loaded
resistor concept.
The old Auburn plugs had a molded-in resistor that seldom
failed, and AC copied that idea but have had some trouble anyway.
Now here's a debate: The resistor was originally to reduce
radio interference in automotive plugs. Since aircraft plugs are
shielded, that's not necessary. The textbooks say that the resistor is
there to shorten the spark duration and reduce electrode erosion.
Wouldn't it be better to leave the resistor out and accept shorter but
consistent plug life?

Dan

wrote:
: Now here's a debate: The resistor was originally to reduce
: radio interference in automotive plugs. Since aircraft plugs are
: shielded, that's not necessary. The textbooks say that the resistor is
: there to shorten the spark duration and reduce electrode erosion.
: Wouldn't it be better to leave the resistor out and accept shorter but
: consistent plug life?

It *may* be acceptable, but the shielding isn't 100". Also, the increased
distributed capacitance of the shielded plug wires would lead to extra-high currents
if there were no resistance in the loop. I think that plug life is already pretty
low... it would probably be horrid without the resistor.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

("Dave Butler" wrote)
The speaker was just laying loose inside the door...

Yum! Speaker eggs.


Yum, food based - finally, you're in *my* wheelhouse.

So, the speaker is now the pencil?


Montblack

My (50 years in the business) A&P has me replace the gaskets each time I
clean the plugs. I never reuse them. He as all the nice equipment that you
mentioned. Easy job.

My mechanic is also very old school. (42 years as an A&P/IA) He's also a
former Grand Champion EAA and AAA home-builder. He's also the guy who
overhauled my engine.

The guy knows his stuff.

If he says the washers can be re-used, so long as you make sure they go back
on the same way they came off (so that the perfectly mated side matches the
under-side of the plug), I believe him.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Airpower has a pretty good deal on NEW Autolite plugs right now, until
Oct 14th.

New $8.95 each

866-287-8506

Karl
"Curator" N185KG

On 9/28/05 09:15, "Jay Honeck" wrote:

If he says the washers can be re-used, so long as you make sure they go back
on the same way they came off (so that the perfectly mated side matches the
under-side of the plug), I believe him.
--
Jay Honeck

Jay,

How should they be installed the first time? There's a flat side and a
rounded side to the washers - which goes toward the cylinder and which goes
toward the plug?

- Don
Whether we call it sacrifice, or poetry, or adventure,
it is always the same voice that calls.
- Antoine de Saint-Exupéry