ballast resistor question
Le Mans Master
Joined: Aug 2005
Posts: 6,526
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From: Temple Terrace Florida
Ballast resistor
My 68 has a ballast resistor wire, not a ceramic resistor like my 66. I do not know what other years have. If the car has points, then you will need to step down the voltage or your points will wear out very quickly. Jerry
Team Owner
Joined: Sep 2006
Posts: 31,212
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From: Westminster Maryland
Hi LT1,
I believe the ballast resistor limits the amperage through the coil.
As EM posted our cars (your 70) didn't have a ballast resistor but instead had a resistance wire.
I believe the ohm rating of the ballast resistor or resistance wire depends on the output of the coil.
Is the resistance wire still in the harness you're using?
From what I've read it appears use 1.4 ohms if you don't know the output of the coil being used.
Regards,
Alan
I believe the ballast resistor limits the amperage through the coil.
As EM posted our cars (your 70) didn't have a ballast resistor but instead had a resistance wire.
I believe the ohm rating of the ballast resistor or resistance wire depends on the output of the coil.
Is the resistance wire still in the harness you're using?
From what I've read it appears use 1.4 ohms if you don't know the output of the coil being used.
Regards,
Alan
Last edited by Alan 71; Mar 4, 2015 at 09:35 AM.
Team Owner
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From: Crossville TN
Also, the ballast resistance (from the coil wire) will be different depending on whether the car was built for a points ignition (which I am assuming that you have) or the transistor ignition (TI). If you have access to the car, you can use an ohmmeter to measure the resistance of the coil wire in place. Just put ohmmeter on lowest resistance setting, one lead touching the end of the (powered) coil wire and the other lead contacting that same wire where it goes into the fuse/electrical bulkhead connector. Use a needle or pin to penetrate the insulation and make contact with the wire.
Le Mans Master
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
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I have a stock points system on my 74 and I pulled back the cloth covering and the wire has 135 ohms imprinted on it.
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
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Le Mans Master
Joined: Dec 2003
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From: Fremont CA
Also, the ballast resistance (from the coil wire) will be different depending on whether the car was built for a points ignition (which I am assuming that you have) or the transistor ignition (TI). If you have access to the car, you can use an ohmmeter to measure the resistance of the coil wire in place. Just put ohmmeter on lowest resistance setting, one lead touching the end of the (powered) coil wire and the other lead contacting that same wire where it goes into the fuse/electrical bulkhead connector. Use a needle or pin to penetrate the insulation and make contact with the wire.
The K-66 system takes it's power off the steering column ignition switch.....full 12VDC at all times no ballast resistor/wire in the system
Racer
Joined: May 2011
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From: Newcastle NSW
http://www.tispecialty.com/articles/article5.htm
http://www.tispecialty.com/articles/66-71diagram.htm
Thread Starter
Le Mans Master
Joined: Oct 2000
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From: Texas-out west
should have said this was on my 67 which did have TI but box failed so rewired to use ballast resistor, remember it ran fine before I stored it.....ask here as well as in c2 section for other imputs to cover all bases, sorry for confusion and thanks for any help.
Le Mans Master
Joined: Dec 2003
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From: Fremont CA
I guess I should clarify my statement.....the electrical feed into the K-66 TI system does not have any ballast resistor in it.....full 12VDC.....yes the wiring of the K-66 TI harness has resistance wire in it but, the system must be provided with a full 12VDC source to properly work.