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12 volt coil

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Dale in Ar.

09-01-2004 20:02:39

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If I replace my 6 volt coil with a 12 volt coil, will I have to change my condencer also ??Also ,with a 12 coil that reads"must use a resister" does that mean that I must use a resister before the coil and reduce the 12 volts down to 6 volts??? thanks

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T_Bone

09-02-2004 20:33:56

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Re: 12 volt coil in reply to Dale in Ar., 09-01-2004 20:02:39

Hi Dale,

Using a resistor lower the voltage to the coil making the points last longer.

When I bought my IH-340U they left on the 6v coil. The engine would run for 15 to 30 minutes then quit until the coil cooled. I switched it over to a 12v coil without a resistor 3yrs ago and it"s been running just great, about 100hrs.

T_Bone

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Kendall

09-02-2004 13:23:57

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Re: 12 volt coil in reply to Dale in Ar., 09-01-2004 20:02:39

If it says "must use resistor" on it, and you're using a 12V battery, then yes you must use a resistor. Otherwise, the coil has resistor built in.(or so the story goes) The resistor is to reduce the current going through the coil. It's the collapsing magnetic field in the coil, when the points open, that makes the spark, not the current going through it. The condenser is same for 6V or 12V. If you run the coil without a resisor, it will get hot in short order, but it will still work, up until it fails due to heat.

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Nebraska Cowman

09-02-2004 04:38:28

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Re: 12 volt coil in reply to Dale in Ar., 09-01-2004 20:02:39

all coils are 6 volts. the ones we call "12 volt" have an internal resistor. No resistor is required for 6 volt systems.

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TheRealRon

09-02-2004 04:58:49

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Re: 12 volt coil in reply to Nebraska Cowman, 09-02-2004 04:38:28

Uh, wrong.

6v coils are 6v coils. 12v coils are 12v coils.

Ballasts are used on 6v coils so that the coil actually "sees" about 4.5v which is their design limit.

For 12v coils, the number is about 9v. Obviously if an external ballast is present you can measure the voltage difference with the engine running. For internal ballast coils, obviously you cannot.

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buickanddeere

09-01-2004 20:24:32

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Re: 12 volt coil in reply to Dale in Ar., 09-01-2004 20:02:39

If the internal resistance is 1.5 ohms the coil can only used on 6-7 volts during continious usage. 3.0 ohms on 12-14V. The 0.6 ohm coils need a intelligent ignition that controls dwell with rpm. The "Ideal" capacitor size varies a some with the coil resistance and rpm operated at.

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