Brand new Sierra coils- 10.4 ohms resistance???

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Active member
Jan 26, 2023
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Rocklin CA
Hi there, I recently bought brand new sierra coils for my older outboard. Ran a resistance test on them with a multimeter before installing onto the magento plate- both read 10.4 ohms. Is this Okay? Does it translate to poor spark? My original coils which I thought had gotten bad still read 4.23 each!
Different coils have different specs, and I can only speak to the vintage-style OMC coils that were used for decades in many of their products.
These coils have two windings, a primary and a secondary.
The primary can be measured between the two leads and should read between 1.0 to 3.0 ohms.
The secondary can be measured between the non-condenser grounding lead and the spark plug stud and should read between 3000 to 10000 ohms.
*you can extend this secondary analysis to the end of the plug wire, too, to gauge the condition of the wire.
You might also want to pay special attention to the units displayed on auto-style meters. Many times a four digit value in the thousands will be abbreviated with a "k" unit.
If you're speaking of a different type, I suspect the measuring of the windings would be the same but the allowable value would need to retrieved from a spec sheet for that particular coil.
That all being said, in the past, I have received brand-new Sierra products that were wildly out of spec. I try to buy oem coils if available.
(Sierra's condensers are nothing to write home about, either)
@Pappy @mbullen please see attached. 1x picture is Sierra and 1x picture is OMC.

I ordered 2x sierra which have the high 10.4 ohms

The OMC page says "for 2-6 hp engines".. but mine is an 18hp..?

Which should I buy?


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