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post #1 of (permalink) Old 08-30-2002, 04:47 AM
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Better performance on a TFI Conversion

I notice that I am only getting 4.75 volts on the (+) side of my TFI coil and I was wondering if it is worth it to drop the resistance wire to around 0.8 or 0.7 ohms instead of 1.35 ohms? This is to make up for the diffence in the coil resistance between stock (1.4 Ohms) and a TFI coil (0.8 ohms)

I realy have no problems with it now and I think it was one of the best improvements I made on my 76 CJ5.

I'm only drawing about 2.5 amps when running and 5 amps when the engine is not running but ignition on.

I also heard about a Dura Spark II module in Ford cars and trucks. Are these any better?? I tried a search and got no matches.
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post #2 of (permalink) Old 08-30-2002, 09:56 AM
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Re: Better performance on a TFI Conversion

From what I've read about TFI coils and the resistors... you've got the right idea. If your coil sustains the voltage increase then it's likely manufactured for full 12 volts. Then the next thing to worry about would be the duration of saturation. That's defined by the Duraspark Module. The Duraspark II, if I remember all TR's lectures correctly was good for about 1/3rd more fixed dwell time which would modify the collapse of the field, affecting saturation.
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post #3 of (permalink) Old 08-30-2002, 10:24 AM
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Re: Better performance on a TFI Conversion

It's a good thing I know what your talking about.

I wonder how I could test how long it takes to reach saturation. I probably could put my scope on it. I figure if it's to long then the voltage might reach a plateau before firing. At that point my dwell will be to long, but with the Dura Spark controling the time I would not be able to tell if the dwell time is to short.

Is the Dura Spark II a direct replacement or are there difference in wiring. Where did TR post lectures about this? Do you have archives ??
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post #4 of (permalink) Old 08-30-2002, 10:38 AM
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Re: Better performance on a TFI Conversion

John, your questons could be answered only by my conjecture. The rise time and dwell would have to be engineered in, however the coil is the modifying factor.

Any time I need to look for something TR's posted it takes a pretty exhaustive search through his posts. It's often like looking for a needle in a Haystack. Then when I do find what I'm looking for I find I've rememembered it worng... and I'm back to square one.

One wish I would have for this Fourm software would be to be able to dump all of a users Posts (or threads, for that matter) to a text file. IMHO that would be a nice feature.
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