Coil resistance on 850 commando???

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Mar 1, 2007
What should be the dc resistance across the plus and minus of an ignition coil on an 850 1974 commando 12v pos earth system????. Spark seems a little weak maybe??? I checked both coils an it seems to be about 1 0hm??? Neither coil is shorted to the tubular aluminum housing.
If those coils are Lucas 17M6 (6V) then the primary resistance should be between 1.7-1.9 Ohms.
It's difficult to say really, as the primary resistance on its own may not show up a faulty coil, unless the reading is way off spec?

A primary reading of 3 Ohms is what I would expect to get for a 12V coil? Are you certain that the coil is 6V (see the base of the coil if it's Lucas) 17M6 = 6V, 17M12 = 12V?

You could try removing the plug cap from the plug wire, then turn the engine over (Ign. on) holding the end of the spark wire close to the head and see how large a gap you can get the spark to jump? Do the same on the other side and compare the results?
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