The correct way to power an HEI - Page 3 -
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Unread 03-07-2013, 05:41 AM   #31
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Matt1981CJ7's Avatar
1981 CJ7 
Join Date: May 2011
Location: Elbert, CO
Posts: 14,019
I think the wiring diagram on page 1 should be a sticky.

The rest of the thread is kind of convoluted.

Just my opinion,


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Unread 03-07-2013, 06:32 AM   #32
1976 CJ7 
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GREAT post .Thanks
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Unread 03-07-2013, 07:58 AM   #33
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1983 CJ7 
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We were pretty well-behaved in that exchange

Live in a way that those who know you but don't know God will come to know God because they know you.
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Unread 03-07-2013, 08:47 AM   #34
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I moderate on a different car forum and yes I would pin this topic.
1983 CJ7 304 V8
1985 CJ7 258 I6
1993 RX7 1.3L Rotary/ GT40R turbo/484 rwhp
2002 F-150 Lariat 5.4L V8
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Unread 08-16-2013, 07:24 PM   #35
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1973 CJ5 
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Bringing back from the dead thread file...

Found out it was an HEI/Clone maker kicking around the CDI ignitions...

Turns out, he was dead wrong.
Comparing the actual firing voltages/duration of CDI to HEI/Clones side by side in my own Jeep...
See, I have dual ignitions, so I set one up for HEI module, one for CDI module, firing through the same coils on the same engine.

No contest. CDI wins hands down.

About 1 in 12 cylinders misfired with the HEI module, where virtually NONE misfired with the CDI at idle,
And it got worse as RPM went up...

The HEI module was so down on power by 2,500 RPM the computer actually registered a fault with the ignition,
Around 1 in 5 cylinders misfired.

When the CDI went from multi fire to single fire (around 2,540 RPM) there wasn't a single recordable misfire up to 4,500 RPM, which as fast as I care to run this little V-8 under load... (also reached the limits of my home made recording equipment)

Now, I understand some misfires at idle or very low RPM with a CDI, since I'm on a carb just like everyone else,
And I'm RICH at lower RPM to keep hesitation down...
But averaging just one misfire in 750 firing cycles is pretty good! Sure beat the 1 in 12 with HEI...
(And at one in 750, I'm not sure it isn't the '73 engine valves/lifters, ect. causing the misfires.)

Now, for those of you that don't know me, I don't leave ANY stone un-turned. I originally built the HEI/DuraSpark ignition to test the difference between those two modules. HEI won in the over all using the Ford type E-core coils, but not by much, and the Ford /DuraSpark ignition showed better cold starts, better hot starts, but lost out to variable dwell and fuel efficiency over time.

Just got around to installing the CDI in the spring, and did a little testing, replacing the DuraSpark module with a CDI module.

And if you are wondering if this is crap or not, several of the guys from this forum have been wheeling with me, they have seen the dual ignitions in action in the field. Just didn't hook up the CDI until this spring...
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