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Unread 08-04-2008, 09:00 AM   #1
pnorris
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Ignition Module on 76 CJ

What would make the module keep going out. I've put 2 on it over the past five years. I don't really drive it that much or it probablly would have went out sooner. The engine will just shut off going down the road. Let it set alittle and it will started back up. I know it's a matter of time before it completly goes out. I have a Prestolite distributor.

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Unread 08-04-2008, 09:54 AM   #2
John Strenk
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Presto Dark you mean.
I havn't realy looked deeply into those modules but the distributor was pretty poor also so I scrapped it. It sounds like something is overheating and it could be the pickup in the distributor (pain to replace) or a cheap aftermarket module. I didn' like the distributor either so I scrapped the whole system and did an upgrade to a Duraspark but that gets really involved with adding additional wire and such.

If you have no burning desire to keep it stock I would recomend a HEI upgrade on you 76 CJ. The improvments are remarkable. Just do a search on the upgrade.
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Unread 08-04-2008, 11:36 AM   #3
pnorris
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What if I used a Motorcraft Ignition Module? Would that work with the Prestolite distributor?
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Unread 08-04-2008, 11:53 AM   #4
jfwireless
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Quote:
Originally Posted by pnorris View Post
What if I used a Motorcraft Ignition Module? Would that work with the Prestolite distributor?

No, it will not work. Get a Motorcraft Dizzy and be done with it.

Jim
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Unread 08-04-2008, 12:14 PM   #5
pnorris
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Call me stupid. I hear it alot and read it alot, but what exactlly is a Dizzy?
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Unread 08-04-2008, 12:45 PM   #6
peanutfarmer101
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A DISTRIBUTOR! .....just short handed
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'78 CJ-7..304 T400.. 30 up front, locked 20 in back(1 piece axles)..Quadratrac w/ parttime conversion..4" lift w/Currie greasable shackles..33" AT's on 15x12 alum wheels
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Unread 08-04-2008, 04:05 PM   #7
rckjeep
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I just did the HEI swap on my 77. Got rid of the whole prestolite stuff, the dizzy, module & extra wiring.
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Unread 08-04-2008, 09:13 PM   #8
JeepHammer
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Quote:
Originally Posted by pnorris View Post
What would make the module keep going out. I've put 2 on it over the past five years. I don't really drive it that much or it probablly would have went out sooner. The engine will just shut off going down the road. Let it set alittle and it will started back up. I know it's a matter of time before it completly goes out. I have a Prestolite distributor.
The aftermarket is ROTTEN for replacment modules right now.
Not a single one I'd trust...
Prestolite makes it even worse!

Since you didn't tell us what engine you have, I can't really recommend anything specific...

How are you set for money?
If you are flush (around $300) I'd switch over to CDI ignition module and a Motorcraft distributor.
Fits your engine correctly and works the best of all the aftermakret stuff.

Some guys will recommend a HEI distributor if you have a I-6 engine...
That's OK if you have an I-6 GM HEI lying around, but if you don't, it's about as expensive as a CDI ignition in the long run...
Besides, there are a LOT of HEI clone makers out there right now selling bad units... Do a search or look through the past few days of posts, there are at least 4 threads running right now about bad HEI clone distributors...

In fact, when I was picking out topics to answer, there is one right under your post!
http://www.jeepforum.com/forum/f8/procomp-hei-problems-590013/

If you have a V-8, you don't have much of a choice,
The Jeep/Motorcraft distributor is the way to go,
And you can use either a CDI module, or a HEI module to switch the coil.
The Jeep/Motorcraft distributor will trigger about all the stock and aftermarket ignition modules, and you can plug in an aftermarket CDI module, or for about $30 you can wire up a GM HEI module...

The choice is yours...

Quote:
Originally Posted by pnorris View Post
What if I used a Motorcraft Ignition Module? Would that work with the Prestolite distributor?
Nope...
Two ENTIRELY different types of trigger systems, so the Prestolite is the one type of (distributor) trigger that won't work with the other types of modules.

Prestolite is a true 'Hall Effect' trigger, and uses voltage to the trigger, and is 'Sensing' a change in that voltage it sent.

Most of the 'Magnetic Triggers' are a 'Modified Hall Effect' trigger and PRODUCE a very small current to trigger the module.
There is no voltage sent to the trigger, so the module 'Sniffs' for any voltage produced in the 'Magnetic Trigger' for a signal to fire the ignition coil.

Last edited by JeepHammer; 08-04-2008 at 09:30 PM..
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Unread 08-04-2008, 09:22 PM   #9
JeepHammer
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Quote:
Originally Posted by pnorris View Post
Call me stupid. I hear it alot and read it alot, but what exactlly is a Dizzy?
'Dizzy' is what the people are that refer to a distributors as a 'Dizzy'...

I often don't reply to people that refer to distributors as 'Dizzy'...
If they don't have the time to spell out distributor, they won't have the time to READ what I write for diagnostic or upgrades,

AND,
They certainly won't have the patients to do the job right,

AND,
I don't want them blaming me for their lack of concentration...
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Unread 08-04-2008, 10:06 PM   #10
jfwireless
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Quote:
Originally Posted by JeepHammer View Post
'Dizzy' is what the people are that refer to a distributors as a 'Dizzy'...

I often don't reply to people that refer to distributors as 'Dizzy'...
If they don't have the time to spell out distributor, they won't have the time to READ what I write for diagnostic or upgrades,

AND,
They certainly won't have the patients to do the job right,

AND,
I don't want them blaming me for their lack of concentration...
I do not particularly like being slammed when all I am trying to do is help. Lots of folks use acronyms, and so do you JH. You provide lots of helpful information to us all, but these type of comments are not helpful at all for anybody and have no place on this forum

Jim
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Unread 08-05-2008, 10:26 AM   #11
_Lou_
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Pardon my ignorance, but what is a "CDI Module"?
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Unread 08-05-2008, 10:42 AM   #12
jfwireless
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Quote:
Originally Posted by _Lou_ View Post
Pardon my ignorance, but what is a "CDI Module"?
Capacitive Discharge Ignition (CDI) See the link below for an explantion.

http://www.vw-resource.com/cdi.html

Jim
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Unread 08-05-2008, 07:46 PM   #13
JeepHammer
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Quote:
Originally Posted by jfwireless View Post
I do not particularly like being slammed when all I am trying to do is help. Lots of folks use acronyms, and so do you JH. You provide lots of helpful information to us all, but these type of comments are not helpful at all for anybody and have no place on this forum

Jim
Probably correct, but they are REALLY annoying to me...

Wasn't slamming you directly, but if you are in the classification, try to upgrade your English...
You are running with a faster crowd, so expect to use the CORRECT terms for things.

'Dizzy' in particular is annoying because it's not an 'Acronym', it's slang and means nothing at all to most people...
The only ones that know what a 'Dizzy' is are those being annoyed by the term, and those using the term to be 'Cool'...
If using gibberish makes you 'Cool', I have a 3 year old nephew that is the 'Coolest' guy on earth....
------------------------

Quote:
Originally Posted by _Lou_ View Post
Pardon my ignorance, but what is a "CDI Module"?
There are two basic types of ignition modules available to you commonly...
One is the basic 'Switching' type module that just switches the vehicle line voltage (around 12 volts) to the ignition coil.

These are called 'Inductive Ignitions', because they use line voltage and an 'Induction Coil' (Ignition Coils are Induction Coils) to provide SPARK ENERGY to the distributor/spark plugs...

A CDI (Capacitative Discharge Ignition) Module uses a bank of Direct Current (DC) storage Capacitors to power the ignition coil.
Instead of the ignition coil trying to Magnetically Saturate on roughly 12 volts,
A CDI module will throw (on average) 400 to 600 volts at the ignition coil.

This increases the ignition coil's output (Spark Energy) by 500% to 1,000% depending on the particular vehicle, the RPM the engine is running at, and a few other variables...

When someone tells you to buy an 'HEI' (A GM trademarked name meaning 'High Energy Ignition') type distributor, what they are talking about is a '60's designed electronic 'Solid State' ignition module that is still switching line voltage and is still only capable of feeding (roughly) 12 volts to the ignition coil...

Where if they know ANYTHING about modern ignition developments, they will recommend a 'CDI' or 'Capacitive Discharge Ignition' Module, and increase the Usable Spark Energy by 500% just by switching from the factory module, to a CDI module.

A lot of your Coils' function, and it's output energy (Spark Energy) is a result of how cleanly the Module switches 'On' and 'Off' the power to it.
The faster, cleaner the power gets switched 'ON' & 'OFF', the stronger the Usable Spark Energy will be FROM the coil to the plugs...

CDI modules switch the power MUCH faster and MUCH cleaner than any of the factory modules...
The Jeep Factory ignitions, Prestolite or DuraSpark modules, or the other common modules, GM HEI type or pretty much any of the aftermarket modules that have come along in the past 25 years or so...

Only recently have the digitally controlled ignition computers in modern cars even come close to the switching speed of CDI modules,
But still can't produce the spark energy since most of them are still INDUCTIVE ignitions (line voltage) where a CDI module has the trump of throwing 400 to 600 volts at the ignition coil!

Some factory supercharged vehicles, and some of the exotic fuel cars (100% alcohol, propane, CNG, ect.) cars have CDI modules from the factory, but for the most part, automakers are stuck using the most 'Cost Effective' way to get the fire lit in the cylinder, and with gasoline cars, the 'Cheap' way is induction, not CDI.

Last edited by JeepHammer; 08-05-2008 at 08:02 PM..
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Unread 08-05-2008, 08:12 PM   #14
kw89425
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jeephammer i have a 258 and i have a msd box i would like to use on it for awhile. mine has the junk distributor. what do i need to be able to use the msd what do i need to look for in the junk yard for a distributor? i cant spend much money because i want the qt case you have
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Unread 08-05-2008, 08:23 PM   #15
JeepHammer
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Quote:
Originally Posted by kw89425 View Post
jeephammer i have a 258 and i have a msd box i would like to use on it for awhile. mine has the junk distributor. what do i need to be able to use the msd what do i need to look for in the junk yard for a distributor? i cant spend much money because i want the qt case you have
Sorry man, there is just NO good way to go about that...
You can put the MSD AFTER your stock ignition, but you will still be at the mercy of the crappy (and usually broken) Prestolite distributor, Small distributor cap, and short rotor...

Start your own thread, and ask for an ignition upgrade for a '76 and I'll look into it where we can discuss it without hijacking someone else's thread.
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