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Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

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post #1 of (permalink) Old 01-24-2005, 01:49 PM Thread Starter
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Ref: RRich,LEVE,others... : Dspark Ign Mod Quandar

Two questions pleeeeeeeeeez. 1.) What is the white wire for in the Duraspark I (I think). It seems to get 12v from same source as for starter solenoid (full 12v to coil for starting). Is this the spark retard lead and if so does the HEI have something build into it to allow easier starting? 2.) Kind of like picking the fly poop out of the pepper question: after seeing the scope pattern of the different ignitions and as a matter of basics, does the coil work with AC or pulsed DC? I have understood in the past that an ignition coil is like a transformer. They produce output voltage with a change in the input voltage. Straight DC only gives you something on the initial rise (????). AC with it's constantly changing voltage is what works. ???? [img]images/graemlins/grin.gif[/img]
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post #2 of (permalink) Old 01-24-2005, 02:33 PM
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Re: Ref: RRich,LEVE,others... : Dspark Ign Mod Quandar

[ QUOTE ]
1.) What is the white wire for in the Duraspark I

[/ QUOTE ]

Like you said, retards the spark during start up. No the HEI doesn't have anything like that so the white wire is no longer needed.

[ QUOTE ]
...does the coil work with AC or pulsed DC? I have understood in the past that an ignition coil is like a transformer. They produce output voltage with a change in the input voltage. Straight DC only gives you something on the initial rise (????). AC with it's constantly changing voltage is what works. ????

[/ QUOTE ]

Again you pretty much answered your own question. Yes an ignition coil is a transformer in that it has two windings with a turns ratio. The act of charging it up and then turning it off causes a very large voltage to be induced and then arc across the sparkplug. While this is a DC circuit it creates an (edit out "AC Voltage") pulsed DC output for spark.

Clear as mud?

RRich is most often better with words....

Dale

Edit: It's not AC because it has no negitive component... the current doesn't alternate with respect to ground, it is direct.
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post #3 of (permalink) Old 01-24-2005, 02:40 PM
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Re: Ref: RRich,LEVE,others... : Dspark Ign Mod Qua

1. White wire from the module goes to the S terminal on the starter relay. It's for the Hot On Start connection. The red wire from the same connector is the Hot in Run feed

For your pleasure wire colors are as follows:

Red: Battery positive.
Orange: To pickup coil.
Purple: To pickup coil.
Black: To distributor (ground).
Green: To ignition coil tachometer terminal.

2. The FOMOCO only retards/advances the timing on a CJ by about +-3*, and it's controlled by the knock sensor in conjunction with the ECM.

3. The coil is pulsed. That's the job of the ignition module. It controls the shape and duration of the pulse to control the saturation of the coil. If you over saturate the coil, it heats up and dies. Over saturation can be due to primary voltage overload or a longer pulse duration causing a long duty cycle for the coil.
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post #4 of (permalink) Old 01-24-2005, 05:55 PM
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Re: Ref: RRich,LEVE,others... : Dspark Ign Mod Qua

DC is used as pulsed DC. On Off On Off.

The coil is a transformer of sorts, but it's an auto transformer (not to be confused with automotive transformer.)
Kinda the same idea as a flyback transformer - kinda.

The primary and secondary are wound backwards as opposed to a regular transformer, and the secondary (bottom end) is tied to the primary (top end.)

And it uses an iron core.

When current flows - module's on or points are closed - a magnetic field builds up - lots of energy goes into the iron core - you can say that energy is "stored" there for awhile. Charging time is called dwell. If it was a regular transformer it would have a big output - 12 volts multiplies by the turns ratio, but this doesn't. You can barely feel it.

Once charged with lots of energy and it's "ready," the module stops current flow.

The magnetic field collapses - a voltage is induced in the secondary like a regular transformer - maybe 500-1000 volts, depending on the turns ratio.

BUT----since it's also collapsing around the primary it too develops a big voltage - about 250-300 volts. Since the primary is feeding the secondary through the internal connection, that voltage gets multiplied by many times - essentially the turns ratio - and that voltage adds to the other secondary voltage.
Makes big spark!

Sounds goofy, but it works. That's called the Kettering principle.

So -- the big secondary spark happens when the primary current goes away!

The HEI just does it better than most everything else.
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post #5 of (permalink) Old 01-24-2005, 10:35 PM
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Re: Ref: RRich,LEVE,others... : Dspark Ign Mod Quandar

Somehow in the "Big Picture" of the board, this thread seems to be lacking the intense detail that one might come across with a simple search.

Goodness, read this thread (slowly or your head will explode):

<u>Interesting Old Thread w/ignition info and more !</u>

It is just slightly shorter than most novels with nearly as much drama. [img]images/graemlins/grin.gif[/img]

I saved it to read it again. [img]images/graemlins/smirk.gif[/img]

Dale
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post #6 of (permalink) Old 01-25-2005, 05:05 AM
 
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Re: Ref: RRich,LEVE,others... : Dspark Ign Mod Quandar

Wow, The Battle of the Titans. Are they going to make a movie out of that post? [img]images/graemlins/laugh.gif[/img]
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post #7 of (permalink) Old 01-25-2005, 12:42 PM
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Re: Ref: RRich,LEVE,others... : Dspark Ign Mod Quandar

Sorry if my answers bore you - I try to be as complete and accurate as possible. Sometimes long winded or covering more than asked.

Flippant, inaccurate, incomplete, or wrong answers just cause problems and misinterpretation.

I've seem too many trail failures because of the old "I heard" or "someone said" answers.

Besides, some folks "want" to know how things work. Others know where the off switch is.

If the consensus of opinion is I shouldn't answer, let me know.
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post #8 of (permalink) Old 01-25-2005, 12:59 PM
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Re: Ref: RRich,LEVE,others... : Dspark Ign Mod Quandar

Well I was afraid that old thread might be poking at something I shouldn't. But I enjoyed reading it and learned a few things along the way (not the least some board history).

RRich your posts are never boring and to me the detail and how things work would be the best part.

Obviously I didn't present the old post in a correct fashion, maybe shouldn't have put it up at all... As stated, I enjoyed reading it and wanted to share that... Be that as it may.

Very Sorry

Dale
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post #9 of (permalink) Old 01-25-2005, 01:51 PM
 
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Re: Ref: RRich,LEVE,others... : Dspark Ign Mod Quandar

[ QUOTE ]
If the consensus of opinion is I shouldn't answer, let me know.

[/ QUOTE ]


Geeesh ,, Rich thats what this board is all about!! getting answers to questions. By all means you should answer [img]images/graemlins/confused.gif[/img]
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post #10 of (permalink) Old 01-25-2005, 01:53 PM
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Re: Ref: RRich,LEVE,others... : Dspark Ign Mod Quandar

That thread is freakin ridiculous. I can't say enough bad things about personalities like that. It's an dismal waste of valuable experience and input.

RRich ~ your replies are informative, insightful, and appreciated. Yes and No often do not suffice, and it's nice to have the "why" explained in such a comprehensible fashion.

BTW~ I saw TR cruisin the other day, and I got a pic of his lastest CJ build...

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