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A_Locomotive Member
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Hello, I am going to replace my ignition coil and plug wires on my JH, I have an occasional miss fire and figure these are the only two parts of the ignition system so havent replaced so might as well and see if it sorts it out. Coil currently on my car appears to he quite old and I cant find much info on it, its a KEM U12A. Electrical isnt my specialty, reading up on coils I believe I need one in the 20-25k volt range amd with 1.5ohm or so since my car is running points and a ballast resistor. What would you guys recommend, anything specific or should I see if I can find a generic one? |
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discogodfather Member 
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There are a lot of options. The ballast resistor is designed to take a 1.5 ohm coil and bring it up to 3 ohms. It protects the points. If you go away from the points into a Petronix, you can leave the ballast resistor out. Then you would look for either a 1.5 ohm or a very low resistance, like a .5 ohm high performance coil. If you keep the points and the ballast then yes, 1.5ohm. There are so many brands out there including stuff from Bosch (blue coils) and the Lucas Sport series, the most important thing is to look at the resistance and get it where you need it. Other than that I have tried many different brands and found no real difference. Some coils are now oil filled as opposed to solid, which supposedly adds to their performance and durability. It's possible to find a Lucas Gold that is around 1.5 ohms, oil filled, and advertised as high performance, but again I have a box of 3-4 different versions and can't tell any difference. The stock system draws amperage through the tach circuit, so it's crude to say the least- not much to do in terms of "high performance" there. |
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A_Locomotive Member
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Arent the Lucas Sport Gold coils 40k volt coils? Looking around online I found very mixed info on running that sort of voltage with points, with pertronix or similar skys the limit it seems but I left the points on my car when I changed them because I like the experience of working on the car. I actually had a pertronix on hand originally but returned it in favor of points once I realized setting then wasnt terribly difficult and I also didnt want to deal with the potential tachometer problems. While digging around online earlier I found a Lucas coil that seems to fit the bill so I think I'll order it, its a DLB102, proper ohms, voltage and I dig how it looks. |
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discogodfather Member
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A_Locomotive wrote:Arent the Lucas Sport Gold coils 40k volt coils? Looking around online I found very mixed info on running that sort of voltage with points, with pertronix or similar skys the limit it seems but I left the points on my car when I changed them because I like the experience of working on the car. I actually had a pertronix on hand originally but returned it in favor of points once I realized setting then wasnt terribly difficult and I also didnt want to deal with the potential tachometer problems. While digging around online earlier I found a Lucas coil that seems to fit the bill so I think I'll order it, its a DLB102, proper ohms, voltage and I dig how it looks. Not sure on the voltage. I run a DLB105, which is the high 3.0ohm resistance version. My petronix is the magnetic older one, not the optical one, never had a problem with the tach. But then again the stock tach is a bit of a joke in terms of accuracy anyway. Last edited on 01-08-2022 03:21 am by discogodfather |
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Esprit2 Member
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The Pertronix 'basic' Ignitor can't handle the high current draw of a coil with low internal resistance. The old/early ones with magnetic switching have no internal self-protection, and will simply fry the first time, every time. The current Ignitor does have self-protection against high-current/ over-heating, and will shut itself down. But sit alongside of the road for about half an hour to allow it to cool down, and it will start to function again. At least until it over-heats and shuts-down again. Don't use a low-resistance coil with a 'basic' Ignitor. Ignitors II & III are okay with low resistance/ high current. But go too nutz, and they too will shut down when they over-heat. But you're going to have to work at it to make them over-heat. When you get to that point, it's clearly your fault. Regards, Tim Engel |
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discogodfather Member
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Esprit2 wrote:The Pertronix 'basic' Ignitor can't handle the high current draw of a coil with low internal resistance. The old/early ones with magnetic switching have no internal self-protection, and will simply fry the first time, every time. The current Ignitor does have self-protection against high-current/ over-heating, and will shut itself down. But sit alongside of the road for about half an hour to allow it to cool down, and it will start to function again. At least until it over-heats and shuts-down again. Don't use a low-resistance coil with a 'basic' Ignitor. Ignitors II & III are okay with low resistance/ high current. But go too nutz, and they too will shut down when they over-heat. But you're going to have to work at it to make them over-heat. When you get to that point, it's clearly your fault. Right, so the chart would be: Petronix II/III (optical, newer) / Low resistance up to 1.5 ohm coil Petronix I (magnetic, older) / 1.5 Ohm coil with ballast or 3.0 ohm coil (my setup) Points / 1.5 Ohm coil with ballast or 3.0 ohm coil Last edited on 01-10-2022 09:13 pm by discogodfather |
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Darth V8R Member 
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I would add to this thread the following: An occasional misfire can indicate a bad condenser. I have had this occur with a new condenser right of the box as well. So if you get an occasional misfire (NOT a backfire) try a different condenser. If the condenser has failed totally, the engine will break up (sputter) at higher RPMs, and you may notice a tendency to burn points. Vance Last edited on 03-11-2023 06:10 pm by Darth V8R |
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