I thought that I would measure the ohms on my Iridium plugs today. 7 of the plugs are Champion and the other is Autolight.

1 top 6.6 mega ohm
1 bottom 2.8 mega ohm
2 top 1.5 kilo ohm
2 bottom 7.7 mega ohm
3 top 4.5 mega ohm
3 bottom 2.4 mega ohm
4 top 24.5 kilo ohm
4 bottom 1.2 mega ohm Autolight plug

No, the above readings are not typos or misreads. Just the facts. Something must be wrong with the 800 - 1,200 ohms listed below. Tomorrow I will remeasure with an analog VOM meter.

The plugs all looked pretty good except for the number 2 bottom. It looked very fouled and was not firing quite right from an in flight test.

I think that I may swap the number 2 bottom's resister with one from an old standard plug.

Thoughts are welcomed.

> From: Isaac Heizer <ijheizer@comcast.net>
> Date: October 10, 2010 10:57:35 AM EDT
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> 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..
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> -isaac
> ES-P N7842K
>
--
Lorn H. 'Feathers' Olsen, MAA, ASMEL, ASES, Comm, Inst
DynaComm, Corp., 248-345-0500, mailto:lorn@dynacomm.us
LNC2, FB90/92, O-320-D1F, 1,750 hrs, N31161, Y47, SE Michigan