OT - coil specs

Brian in Wheeling

Brian in Wheeling

Senior Member
I have a Lucas Q12 coil dated 8/47.
What should the coil resistance measure? I show 4.5 ohms on the primary and 17.08K on the secondary. This takes in account the resistance of the meter leads. I know coils can test good on the bench but fail when placed in service/ hot, but I am just trying to see if this is within a good range. It is a solid coil, not oil filled. An old Lucas unit for a British car.
Thanks,

Thanks for your info.
Brian W.
 
wow. Lucas electrical components were one of the biggest single reasons that England's car industry bit the dust. The reliability is non-existent. But for some reason every English car manufacturer used Lucas. They just didn't get it, and they paid a big price. I have had the misfortune of working on many English cars, including Rolls, and was able to observe first hand the obviously poor quality of everything Lucas (Prince of Darkness) made.
 
I'm not familure with the Lucas coil readings, but thought those sounded a little high as if it was designed for 12 volts. With a date of 8/47, there weren't many cars running 12 volts at that time. You could hook it up and try it and my bet would be on it working, even on 6 volts. When the engine is off, but the key is on and points closed, the Model A coil will draw about 4 amps. When the engine is running the coil draws about 1 to 1 1/2 amps, depending on RPM. This Lucas coil would draw less since it has a higher ohm reading, but I still think it will work.

We were posting at the same time, but I've also heard the same thing about the prince of darkness.
 
Last edited:
Tom:
It is a 12 volt coil. I was told older made coils with solid cores, not oil filled, draw higher resistance due to more windings of finer wire. Don't know of its true.

I have never believed the popular myth and jokes about lucas quality, I have many original Lucas parts going strong after more than 50 years, and most of them can be rebuilt. I have worked on cars with Lucas electrics for over 40 years....back when they were new even!

Brian W.
 
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