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12-08-2012, 08:40 PM | #1 |
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Spark plug resistance
I noticed, in the dark, that a couple of plugs were jumping down the porcelain to ground. I pulled one and checked for cracks ect. I cleaned the terminal end, and the center electrode, and ohmed it out. Theses are 3X's by the way. I'm losing 1.9 ohms compared to a new plug. Isn't this a solid piece of metal? Where's the resistance coming from?
I'm running an electronic ignition as well. Thanks Chuck Last edited by Chuck Sea/Tac; 12-08-2012 at 08:45 PM. Reason: Forgot info |
12-08-2012, 10:42 PM | #2 |
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Re: Spark plug resistance
The center electrode is inserted into the center of the brass connector. I assume it's a slight interference fit. However it appears corrosion sometimes develops within that contact area causing resistance. I have one or two NOS 3X cores that have no continuity whatsoever.
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12-08-2012, 11:27 PM | #3 |
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Re: Spark plug resistance
Chuck,
Hope not to sound offensive, Plugs are an expendable item. We can't expect miracles from old used up plugs. Sorta' like lookin' at a defunct frosted house bulb, "Well, it sure looks good!!" Bill W.
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12-08-2012, 11:39 PM | #4 |
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Re: Spark plug resistance
Some spark plugs have a built in gap, so they will always show open with an ohm meter.
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12-08-2012, 11:47 PM | #5 | |
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Re: Spark plug resistance
Quote:
I recomember those, the # had an "R" and they had a vent hole in the top to let the ozones, or whatever, get out. Bill W.
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12-08-2012, 11:50 PM | #6 |
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Re: Spark plug resistance
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12-09-2012, 12:01 AM | #7 | |
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Re: Spark plug resistance
Quote:
I thought they were old plugs-----I told the Dog to make note of this in his "WEIRD HAPPENINGS" notebook. Bill W.
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12-09-2012, 12:28 AM | #8 |
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Re: Spark plug resistance
1.9 ohms never stopped 10,000 volts. Something else is going on. Is this the coil that is supposed to be on the car or a super high output coil? How do you know it is not jumping the plug gap? Does the engine miss? If a very high voltage it may be a 'halo' effect of the spark jumping the gap and down the side of the porcelain
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12-09-2012, 12:36 AM | #9 | |
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Re: Spark plug resistance
Quote:
I would not worry about 1 ohm. The current is not much, so the voltage drop is not much (compared to the 20,000 volts available). Clean and dry the outside of the porcelain well on all the plugs and check again for spark leakage. You should be good to go.
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12-09-2012, 12:38 AM | #10 |
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Re: Spark plug resistance
Not 3X plugs!
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12-09-2012, 10:57 AM | #11 |
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Re: Spark plug resistance
As far as I know, the "R"in the plug number indicates a resistor element built in to the plug. These are for modern cars, and the resistor helps to suppress the noisy emissions that woudl otherwise mess up your electronics-and your radio reception.
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