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Join Date: Apr 2010
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Resistance sparkplug wires - Replace?

I read in the bentley manual about the resistance the sparkplug wires (total) should have on my '83 SC.

Measured all six wires with the following results. Should I replace them?

1: 2,00
2: 2,09
3: 2,00
4: 2,01
5: 2,18
6: 3,67

Old 11-29-2014, 08:37 AM
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The wires themselves are stranded copper with no resistance. The connectors on either end have the resistance and may need attention, particularly on #6.
Old 11-29-2014, 09:25 AM
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I don't fully understand what causes the resistance. The numbers you are seeing, one thru five wires, are right around 2,000 ohms. #6 is pushing 4,000.

If I remember correctly, my 81 was in the mid-2000's but all within a hundred ohms or so of each other.

If they are the shielded Beru wires, try fiddling with #6. Not sure how to repair them but there are threads about replacing the ends.
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Old 11-29-2014, 09:46 AM
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According to the manual the resistance should be 3k ohm (or 4?). That would mean the other 5 have issues, not nr 6?
Old 11-29-2014, 09:52 AM
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I recommend testing the entire length of the secondary voltage path.

Remove the distributor cap, then measure from the underside - each terminal to the end of the spark plug connector. Compare with specs.

Be aware that too much resistance is NG as it limits the voltage needed to jump the spark plug gap. Under certain conditions, mileage, driving style, gap wear, etc., the available voltage may not be high enough resulting in a misfire.

You may also have resistance spark plugs which add to the total secondary resistance. Suggest using non-resistor plugs.

Reasonable sources suggest 4K ohms or less.
Tempest Tech-Tips - The Right Way to Check Spark Plug Resistors

Sherwood
Old 11-29-2014, 10:13 AM
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Great, thx!

Old 11-29-2014, 10:22 AM
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