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02-15-2020, 02:30 PM | #1 |
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Coil Testing With Multi-Meter
I had posted this question on another thread but no one ever made comment to it so I'm hoping this one will get some responses:
I just read an article that showed a coil can be tested with an ohm meter by checking across the two small posts and then checking from one small post to the spark plug connector. This was for the Model A but did not give any spec's as it said "Determine the resistance using your multimeter and check to see if it's within the acceptable range". What is the acceptable range on a 6V coil on the Model A? |
02-15-2020, 03:31 PM | #2 |
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Re: Coil Testing With Multi-Meter
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02-15-2020, 03:35 PM | #3 |
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Re: Coil Testing With Multi-Meter
If you didn't see this it may also be helpful.....
https://www.fordbarn.com/forum/showthread.php?t=276467 |
02-15-2020, 10:57 PM | #4 |
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Re: Coil Testing With Multi-Meter
PalAl Thanks for responding to my thread. The first one has the information I was looking for. To be honest the second one has my comments asking the above question which no one answered.
Again, thanks for your interest! |
02-16-2020, 12:16 PM | #5 |
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Re: Coil Testing With Multi-Meter
Sorry about the second one, I didn't know how to remove my mistake.
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02-16-2020, 01:38 PM | #6 |
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Re: Coil Testing With Multi-Meter
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02-17-2020, 01:19 PM | #7 | |
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Re: Coil Testing With Multi-Meter
Quote:
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02-17-2020, 01:29 PM | #8 |
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Re: Coil Testing With Multi-Meter
The secondary is fine wire and that's the one that can open up with excessive heat for the most part. The modern coils for 12-volt specifically are around 3 ohms. The old stuff used with 6-volts and ballast resistors for 12-volt are generally pretty close to 1.5 Ohm.
The old coil testers were turned on to preheat the coil to get a test that is more in line with an operational coil since many times they break down after they are warmed up a while. |
02-17-2020, 02:45 PM | #9 |
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Re: Coil Testing With Multi-Meter
With resistance measurements you can condemn a totally bad (open winding), but you can't confirm it's good--- but you need a more dynamic test-- and a hot coil , many will check ok by resistance, and make ok spark cold,
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02-17-2020, 10:16 PM | #10 |
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Re: Coil Testing With Multi-Meter
I had new coil that would not fire the plug under compression. How ever it worked fine
on the bench
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02-18-2020, 02:00 PM | #11 |
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Re: Coil Testing With Multi-Meter
There may have been other reasons it wouldn't get spark at the plug. I bomb test spark plugs for the aircraft on a regular basis and the usually spark much better under compression that they do in open air. Bench testing is a marginal test. Just about any test without an oscilloscope and preheating is a marginal test.
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02-19-2020, 11:41 AM | #12 | |
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Re: Coil Testing With Multi-Meter
Quote:
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If you don't hear a rumor by 10 AM, start one!. Got my education out behind the barn! |
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02-19-2020, 07:43 PM | #13 |
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Re: Coil Testing With Multi-Meter
Compressed air, say 120 psi, ionizes better than ambient air pressure. If you ever use a spark plug tester, you can see it.
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