Spark Plug 20K Test

[Murray40Rider]

Be nice to have consensus on acceptable 20K test values for Resistor plugs and non-resistor plugs?
Best to test hot or cold?
Cold 20K test results for new:
Non-resistor BS 491055T plug = 4.88. Continuity - no. External ground – no.
Non-resistor BS 694385 plug = 8.01 Continuity -no. External ground -no.
Resistor OILE K6RTC plugs (3 tested) = 0.0. Continuity – yes. External ground -no.

Comments, test values welcome.

 

[bertsmobile1]

Absolute resistance values are by & large meaningless
If you press hard on the probes, most meters will give a different reading to just touching
Add to that the actual surface
A slightly oxadised surface will give a different reading to a highly polished one which will again be different to freshly cleaned one.

 

[Hammermechanicman]

Resistor plugs can be anywhere from 500 to 4000 ohms when new. Nonresistor somewhwere around 0 to a few ohms. Unless dealing with aircraft engines with expensive plugs in a can't fail situation not sure what the exercise is about. There is a Mil-spec for spark plug resistance for aircraft engines. Not sure it would apply to small engine plugs.

Tempest At5K Resistance Tester | Aircraft Spruce

Tempest At5K Resistance Tester High internal resistance in spark plugs is rapidly becoming a concern that many IA/AP's are beginning to recognize as the source of rough running engines and chronic magneto related problems.

www.aircraftspruce.com

Aviation Spark Plug Testers 110V And 220V | Aircraft Spruce

Aviation Spark Plug Testers 110V And 220V Designed to clean and test all 14mm & 18mm massive and fine-wire electrode aviation sparkplugs.

www.aircraftspruce.com

 

[StarTech]

Be nice to have consensus on acceptable 20K test values for Resistor plugs and non-resistor plugs?
Best to test hot or cold?
Cold 20K test results for new:
Non-resistor BS 491055T plug = 4.88. Continuity - no. External ground – no.
Non-resistor BS 694385 plug = 8.01 Continuity -no. External ground -no.
Resistor OILE K6RTC plugs (3 tested) = 0.0. Continuity – yes. External ground -no.

Comments, test values welcome.

You have some wrong info posted.

The Briggs 491055T is a RC12YC plug which is a resistor plug.
The Briggs 694385 is a RC14YC plug which is a resistor plug.
The K6RTC appears to be inductive resistor plug. Inductive resistance plugs usually read around 40 ohms but on a 20 kilo ohms scale will look more like zero ohms. Usually used in CDI systems.

 

[tom3]

And keep in mind that for low resistance readings the wires on the meter actually give a reading. Need to have a meter that will zero out that.

 

[Hammermechanicman]

Measuring random new plugs with a Fluke 87V
CHAMP J19lm. 0
Ngk BPR6ES. 4.8K
NGK BPMR7A. 10.2K
CHAMP. RC12YC. 34.5K

 

[Scrubcadet10]

i just use the plug the engine maker recommends.

 

[Hammermechanicman]

i just use the plug the engine maker recommends.

That makes too much sense.

 

[StarTech]

And keep in mind that for low resistance readings the wires on the meter actually give a reading. Need to have a meter that will zero out that.

 

[StarTech]

And keep in mind that for low resistance readings the wires on the meter actually give a reading. Need to have a meter that will zero out that.

Or simply use the old separator tube and add or subtract meter lead resistance. But really need to pull that milli ohm meter when it is a critical measurement.