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GT40R Coil, How many Ohms?

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gtv6capri
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2015/03/10 15:43:55 (permalink)
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GT40R Coil, How many Ohms?

I am about to swap to Pertronix electronic ignition, it needs a minimum of 3 Ohms.  My car currently has a new GT40R coil but I cannot find the Ohm rating anywhere.  Does anyone have a clue as to the rating or do I need to buy one of the matching Pertronix coils?

Capri The car I always promised myself
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    cosworthfreak
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    Re: GT40R Coil, How many Ohms? 2015/03/10 18:42:46 (permalink)
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    Ignition coils with the R are used with a Ballast resistor (which is about 1.8 ohms) which then reduces coil input voltage to 9V. Coils without the R get the full 12 volts from the battery. Sounds like you need the non-R coil.

    Cheers
    Jamie
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    RS 2000
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    Re: GT40R Coil, How many Ohms? 2015/03/10 21:31:43 (permalink)
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    Typically they are 1.2-1.4 ohms

    Cheers

    1979 RS 2000 - SR20DET
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    gtv6capri
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    Re: GT40R Coil, How many Ohms? 2015/03/11 08:53:11 (permalink)
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    Cheers, Pertronix sell a coil matched to their module, for about $59 I think I'll just get it that way the system works as it should, I was asking about the GT40R as I had bought it new and didn't want it to go to waste.

    Capri The car I always promised myself
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    Re: GT40R Coil, How many Ohms? 2015/03/11 10:33:37 (permalink)
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    You can run gt40r with ballast(as per stock setup) and it will run perfect with Pertronix as it was designed as points drop in module and will run at 9v without any issues. If you want to run it at full system voltage you have to run appropriate resistance 12v coil such as recommended 3 ohm one.

    R coil with ballast resistor/harness = 12v 3.0ohm coil

    If you already have a new gt40r use it.
    Cheers

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    jp63
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    Re: GT40R Coil, How many Ohms? 2015/03/12 19:46:39 (permalink)
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    With the Petronix kit you will have to have 12v ignition to the red wire don't put it on the coil if you still have a resistor inline they don't work to well . The Petronix coil will has a lot better output than a gt40 coil but if you already have one it will be fine
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    gtv6capri
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    Re: GT40R Coil, How many Ohms? 2015/03/12 21:23:35 (permalink)
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    Cool, good advice.  There is no obvious resistor in line, I think Ford used different spec wire or something to reduce cranking voltage to the coil

    Capri The car I always promised myself
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    RS 2000
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    Re: GT40R Coil, How many Ohms? 2015/03/12 23:16:36 (permalink)
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    gtv6capri
    Cool, good advice.  There is no obvious resistor in line, I think Ford used different spec wire or something to reduce cranking voltage to the coil


    Ford used resistive wire to drop voltage to the coil. While cranking however the resistive wire was bypassed and full battery voltage supplied to coil.

    Cheers
    post edited by RS 2000 - 2015/03/12 23:23:35

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