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Date: Fri, 27 Jan 2012 11:06:49 -0500
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From: Tim Olson <Tim@myrv10.com>
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Subject: Re: [LML] Re: Champion Spark Plug Resisters
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I *think* the Tempest plugs are the old Unison plugs.  Tempest
bought everything from them and then started manufacturing
them.  In the case of the standard plugs, I don't know if they
made any changes to the design or not.  But, like me,
you're using fine wire plugs and from the stuff written
below, these removable resistors seem to be particular to
Champion plugs.  I'll have to look at mine next time I
clean them, but I seem to remember seeing that the resistors
were one of the selling points on the unison plugs and
that they're continuous material built in to the electrode
area. So they would be non-removable.  So we would just
ohm the plugs out and then pass/fail them.
Tim


On 1/27/2012 6:52 AM, Isaac Heizer wrote:
> John Schroeder said:
>
> This is a new thread for me. I have a Continental IO-550N2B on an ES.
> Where are these resistors located? What do they look like? We currently
> have Tempest Iridium plugs installed.
>
> Here is the start of the saga, so far as I know:
>
> From: 	Isaac Heizer <ijheizer@comcast.net>
> Sender: 	<marv@lancaironline.net>
> Subject: 	Slick Magneto and Spark Plugs
> Date: 	Sun, 10 Oct 2010 10:57:35 -0400
> To: 	lml@lancaironline.net
>
> 	Message Header <http://lancaironline.net/lists/lml/Message/56099-H.txt>
>
> Undecoded Message <http://lancaironline.net/lists/lml/Message/56099-P.txt>
>
> I had a very interesting telephone conversation Friday with a fellow
> from "Aircraft Magneto Service" of Bainbridge Island, Washington
> (www.aircraftmagnetoservice.calls.net). It was prompted by the 350 hour
> inspection of the dual pressurized Slick magnetos on my TSIO-550E.
>
> .......
>
> Then we started talking about spark plugs: I mentioned my plane has
> Champion fine wire plugs. He said all plugs have an internal resistor,
> and for some reason the resistance of many Champion plugs seems to
> increase as the plug ages. Once the plug has been cleaned, the
> resistance can be measured with a standard ohm meter between the center
> electrode and the connection inside the plug barrel -- all new plugs
> should have a resistance somewhere around 800 - 1200 ohms. If the
> resistance ever measures above 5000 ohms, the plug should not be used.
> The fellow told me plugs having too high of a resistance can/will cause
> misfiring and potential problems with the magneto coil and or plug
> harness. A spark plug bomb tester might show this plug as good, so the
> ohm meter test should always be performed every time the plugs are serviced.
>
> Unlike an Autolite plug, a Champion spark plug resistor can be changed.
> Look inside the barrel of a Champion plug and notice the slotted screw.
> Remove the screw and the resistor will fall out: it looks like a slug of
> carbon about 1/2 inch long and maybe 1/8 inch diameter. You can put the
> ohm meter on either end of this slug and measure the resistance -- this
> is the element that needs to measure from about 800 to 5000 ohms. The
> resistor is apparently common among all Champion plugs so he recommended
> visiting your pile of old plugs; removing the resistors; and saving the
> resistors that measure "good". When you run across an otherwise
> servicable plug whose resistance is too high you can change its resistor
> for one from the "good" pile. He says this can cure a host of otherwise
> mysterious "rough running" problems and forestall future problems.
>
> He said some Reno racers remove the resistor and replace it with a piece
> of copper wire to get a much hotter spark for racing. Says it wears out
> the spark plugs very quickly -- but does make a performance difference.
> Is this true?
>
> -isaac
> ES-P N7842K
>
>