Spark plugs

[Dougt]

Noel, one thing to watch out for is the scale you are using on the meter. Are you using a plain ohm scale or the Kohm or Mohm? Some of the newer meters are auto ranging so you need to be careful which scale it's on. 1/2 an ohm would be a lot different than 500 ohms if it was a Kohm scale. The reading you got just shows the continuity of the electrode which most likely isn't going to cause a miss. Lower resistance to ground up inside the plug is what usually causes a misfire. An open in the electrode would weaken the coil over time. I have seen that happen with resistor plugs. They aren't recommended for magneto operation.

 

[Propane1]

Doug, the tester was set on continuity beep, but also showed a reading.

Noel

 

[dodge trucker]

One wasn't an RH10c was it? (R. stands for resistor? I have never done that test before but there isn't enough ohms difference there to matter. Isn't the spec for ohms on (resistance core) plug wires something like 10k ohms per foot of length?

 

[Cvans]

Another thing my genius mind, hehe, figured is, that the copper core in the spark plug, would it gain resistance over time,

Yes and no. Make sure that both places you are touching your probes to are clean and free of carbon or oil. That could be the difference your seeing. The electrode can build up contaminants which will impede it's ability to arc properly.
PS. I'm not a plug expert but have used an ohm meter a lot.

 

[Dougt]

Doug, the tester was set on continuity beep, but also showed a reading.
Noel

That most likely is auto ranging. Notice the ohm symbol on the lower right? It could have a K or an M in front of it when you test like that. I like to hit the range button and lock it in a range I'm expecting to see so it doesn't trick me. Forgetting about the auto range has got me more than once.

 

[olcowhand]

That most likely is auto ranging. Notice the ohm symbol on the lower right? It could have a K or an M in front of it when you test like that. I like to hit the range button and lock it in a range I'm expecting to see so it doesn't trick me. Forgetting about the auto range has got me more than once.

I never learned all the settings on any of my meters, but somehow I get by. LOL

 

[Propane1]

Nope, not a R plug, dodge trucker. I did try the test on a resistor plug. No reading and no beep. Indicating no continuity. but spark will still go thru ????

Noel

 

[Propane1]

Doug, I did see another setting that showed the K then the M and it also said Auto. So I think I was on the right setting.

Noel