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  #1  
Old 10-25-2003, 05:15 AM
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Question Ignition system 101

I am fairly new to the world of Mopar. I have run a bunch of other cars, and moddified them too so its not like I never lifted a wrench. I guess I'm strugling in part by differences in UK/USA terminology but also the ignition system on Mopars seems different (at least from what I read and people talking on here)

So can some kind person explain to an English newbie and former GM owner about Mopar ignition. (or point me in the direction of a website that explains it all)

When people are talking about orange boxes or chrome boxes what exactly are we talking about? Which is better for what and why?

And where/when do ECUs come into it? I assumed thats like the electronic controls you get on late model injection cars but I heard people talking about that for early models too.

I apparently have a "lean burn" ignition on my 5th Avenue. Sounds like a zero for performance to me. Is the lean burn something added to it or is it a particular type of distributor?

Anything else you might like to share with me to help a guy out?
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  #2  
Old 10-25-2003, 07:15 AM
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The Orange box and Chrome box ARE Ecu's ( Electronic control unit's). Most people call them ignition modules. These are the boxes on the fenderwell that help to control spark. Orange and chrome are color codes for different RPM and performance ranges. Orange is better for mild build and street use, it's good to 8000 I believe. For Lean burn, this is a computer control for fuel delivery for better optimizing. Sucks for performance. I would toss it, get a MP recurve dist w/ Orange box, and switch to a Thermoquad carb and a nice dual plane intake....
Just a couple of thoughts...
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  #3  
Old 10-25-2003, 09:19 AM
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In addition to Ausydad, the MoPar ECU's should be looked at in this manor.

Orange box. A better than stock replacement ignition with a hotter spark. Mopar lists this box untill 6000 rpm. Goood for general replacement to mild HP use. Use this as a replacement box for mild hop ups on the engine.

Chrome box. This is a chromed unit used for a hotter set up than just mild bolt on upgrades. Delivering a hotter spark and covering more RPM than the orange box. OK for a street/strip hot rod car.

Gold box, Mopars top of the line power unit in this style of ECU, they say it's good till 10,000 RPM and will handle high current coils. This RACE only ECU should not be used on the street for long periods of time.

MoPar now also sells a CD ignition made by MSD that plugs right in. This Multiple Spark Discharging units are much better for mileage, power and emissions. Weather it's from MoPar or Autotronics them selfs, the maker of MSD.

The lean burn system was designed to reduce tail pipe polution in the late 70's. This ECU was mounted on the aircleaner. MoPar tries to make a HP unit to replace it, but problems continyed. It was dropped. The leanburn units have a history of just dropping out and cutting off while driving. These units should be disconnected infavor of any of the above ECU units.
The distributor used on the lean burn units do not have a vaccum advance control on them. (I'm not sure on this one, it's been a while since I have seen one, but I THINK theres no springs inside ethier.) The computer handled all distrib. dutys.

IMO, use a MSD 6 or 6A (Rev control) and coil with a vaccum advance distrb. This is the best bang for the buck, er pound.
Don, Cuda66273, can do you a distrib. set up for you easy. Just give him the specs of your intended set up and weight of car. This way it's just a drop in and time.
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  #4  
Old 10-25-2003, 11:36 AM
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JUst another note: The orange box has a high failure rate and performance drops off at higher rpms with it over a stock box, but low to mid range it out performa the stock box.
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  #5  
Old 10-25-2003, 11:49 AM
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Thanks for the help so far. But I'm still kinda confused. Normally I have 60s British or GM stuff and theres just a coil, distributor (with mech and vac advance) and thats it (except the leads & plugs...)

What exactly does the ECU do?

Does it replace the advance on the distributor? Vary current/voltage to control the spark power at different revs? How does it get its input to do this?

My wife has a modern car with an ECU but this has a bunch of sensors connected to it (Lamda, air, TPS, etc.) which I don't see on my '68 Fury and I'd be surprised if I had on the '86 5th Ave although it is rather buried in pipes under there.

I always regarded the period after 1973 as a place I didn't want to go car-wise so a lot of this is way new to me as I've driven the last 15 years or more on pure 50s/60s technology...


If I got an MSD on a Mopar it would replace this ECU? Is it a Mopar specific MSD unit you'd need? Not that I'n necessarily going for one (might be overkill) but I'm trying to get this all straight in my mind.

(Thanks for not ragging on me for admitting to owning GM!
)
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  #6  
Old 10-25-2003, 05:14 PM
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The ECU is the control box for sending spark out. The distributor sez when. It does not replace the advance on the distrib. Inside the distrib, theres springs for a mech. advance and the bell on the out side for vaccum advance.
An MSD control unit will replace the stock box on the wall. Thats it. It is better than all the rest and not overkill. They are universal. Not MoPar specific unless you by the MoPar box which plugs into the stock wiring harness. That would be MoPar specific.
Quote:
Vary current/voltage to control the spark power at different revs? How does it get its input to do this?
No.
Jacobs has a system that does this. It gets the info from your foot on the gas pedal. When you press it passed a certain point, you trip a lever that you installed from jacobs to open the flood gates on voltage. Bamm, MAX power.
Quote:
Thanks for not ragging on me for admitting to owning GM!
Your here for your MoPar. Owning other makes is not a crime. Just a fact of the world.
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  #7  
Old 10-25-2003, 05:21 PM
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Compare the MOPAR electronic ignition system to the GM HEI. This will give you a better idea of how it works.

Both systems use a reluctor and a magnetic pickup, instead of points. Both systems still use mechanicle and vacuum advance.

The GM HEI has the ECU/ignition amplifier inside of the distributor. The MOPAR system has placed it external to the distributor.

The ECU/ignition amplifier just takes the ignition signal from the pickup and then triggers the coil. The different color boxes support higher RPM ranges and provide longer spark times (dwell).

The MSD and Jacobs systems are both superior to the MOPAR ECUs.
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  #8  
Old 10-26-2003, 01:40 AM
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thanks ive been wanting to know this aswell.

only question now is:

the mopar CD ignition thing...made by msd? does it plug into stock harness?


is it cheaper then the 150 for the msd 6A box?
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  #9  
Old 10-26-2003, 01:59 AM
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SK, in order asked.

1 yes
2 yes. On the systems using the wall/fender mounted ECU box's like the orange & chrome.
3 I don't think so, you'll need to check that out to be sure.
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  #10  
Old 10-26-2003, 05:53 AM
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Thanks guys, I get it now! (Don't feel such a dumb newbie...)
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  #11  
Old 10-26-2003, 11:52 AM
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On Your 5th Ave , The lean burn system should be eliminated. a mopar electronic ign kit. would be a good place to start. also the carburator needs to be replaced at the same time. You could replace it w/ a 2bbl from an earlier 318 engine or a holley 2bbl replacement carb. would work too. Another option would be to replace the manifold w/ a 4 bbl. type and a small Holley 4bbl carb or a Edlebrock 4bbl. carb. The lean burn was a poor peforming troublesome system. I had a 1984 5th Ave. which ran poorly. I dumped it (the lean burn) and the car came alive!
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  #12  
Old 10-26-2003, 11:56 AM
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68fury;

No problem. Consider this place school then.
Don't feel dumb at any time. Just ask. We all do.
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  #13  
Old 10-26-2003, 02:07 PM
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Quote:
Originally posted by nhdriver
I had a 1984 5th Ave. which ran poorly. I dumped it (the lean burn) and the car came alive!


I'm glad I'm getting consistant advice here!

When I get back off vacation its bye-bye lean-burn
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  #14  
Old 10-26-2003, 10:23 PM
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thanks rumblefish;

i like how you and DWC started this answer by numbers thing to all my rampant questions...keeps it simple
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  #15  
Old 10-27-2003, 12:22 PM
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Default This is my first post...thanks for listening

I own a '70 Challenger and would like to convert it over to electronic ignition. I'm completely ignorant when it comes to electronics. Can someone tell me where to find information to do this conversion? Thanks.
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  #16  
Old 10-28-2003, 02:58 AM
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Mopar dealer sells it all in a kit with instructions or get an msd box for around the same money with instructions included.
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Old 10-29-2003, 08:41 PM
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I got a freind with a lean burn system on a 89 318 fifth avanue and he is wanting to get rid of it. Now if I understand you guys right all he needs is the kit from MP to go to the electronic ignition?? He is planning on putting a 4bbl on it and I was wondering if he could use an non lean burn distributor off an older or newer V8 if so what would year range would be the best?? Also what has to be changed in the wirring harness? keep in mind that this car is fully loaded , power seats,windows,mirrors and AC.
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Old 10-29-2003, 10:24 PM
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SK;

You'll see often, DWC and I think alike. But not identical.

TrxR;

Right. All he needs is the kit. (And a few small parts from Radio Shack. Connectors and shrink wrap or tape. Wire stripers if you don't have them.)
He could use a lean burn distrib, but the ignition kit from MoPar comes with distributor, wireing harness, ignition box and ballast resistor. The kit has instructions that are easy to read, understand and follow even for a first timer.
The lean burn distributor dosen't have a vaccum advance unit on it. It is on the leanburn computer, and will be junked with it.
You'll need to tap into the stock harness. Now don't fret. Some (German) Detuch (sp) connectors from radio Shack or a simple splice into the wire is all thats needed. The wire to splice is in the directions. Just read. It is easy.
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Old 10-29-2003, 11:04 PM
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Actually there is only one splice to make into the cars harness. Two wires in the kits harness goes to the coil, two to the dist. connector, and one to the balast resistor. It's pretty easy.

If your friend wants a 4 bbl on this engine use the stock thermoquad intake or the Weiand action plus with a thermoquad carb. It's more throttle responsive than any holley and it will get better mpg than any holley if you keep your foot out of it.
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Old 10-30-2003, 02:33 AM
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and the MSD 6 or 6AL box connects just as easily?

for the same price as the factory kit;id think the MSD box would be the better choice...considering if you already have the dist. with the vac advance on it.

one more question...the ballast resistor is located where?

as you can tell i havent torn it apart to see where everything goes yet,but am glad u guys added those last 2 posts,seems as simple as the GM HEI set up to me,should be able to pull this off easily.
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Old 10-30-2003, 08:55 AM
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I could be wrong about this but I believe the lean burn dist. did have a vacuum advance & had dual pickups, one set is advanced/retarded by I think 6* compared to the other . The dual pickup dist. can be used as a single pickup or used as a high speed retard system by installing a switch on the dist. leads.
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Old 10-30-2003, 12:28 PM
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The lean burn has the vacuum advance on the lean burn computer and it was never on the dist. The dual pick up is not used on all lean burns and one was used to start the car on and the other is a run pick up and they can not be used as a retard as you sugested.
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Old 10-30-2003, 12:32 PM
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Quote:
Originally posted by SK
and the MSD 6 or 6AL box connects just as easily?

for the same price as the factory kit;id think the MSD box would be the better choice...considering if you already have the dist. with the vac advance on it.

one more question...the ballast resistor is located where?

as you can tell i havent torn it apart to see where everything goes yet,but am glad u guys added those last 2 posts,seems as simple as the GM HEI set up to me,should be able to pull this off easily.
Yes, the msd would be the best set up for hte price and you can use your old dist. Also a set of advance springs for your dist. from mopar performance would be a plus too.

The ballast resistor is made of white porcelin mounted on the firewall near the dist on either side of it. Should have 4 connectors, two on each side. The kits will tell you which connector on the passenger side of the ballast to connect it too. It's about an 1 inch tall 3 inches long and 1/2 inch thick.
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Old 10-30-2003, 12:33 PM
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They most defnitely can be used as a retard by using a double pole , double throw switch on the dist. leads.
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Old 10-30-2003, 01:17 PM
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my 1984 D 250 originally had a carburetted (thermoquad) 360 in it. it also had what i think was the leanburn system... at least, that is what i was told. it did have the dual pickup distributor, and a relay on the firewall that switched the pickups when the key was released from the 'start' position to the 'run' position. it also had a vacuum advance on the distributor. i KNOW this because i had to replace that vacuum advance! if it EVER had a computer of any sort, it is still there... cause i have never found it.

it did have a couple of boxes on the left fender that had 3 wires plugged into them (these were smaller than a pack of cigarettes). what they did, i never bothered to find out. what i do know about them is that while i was lengthening the wires for my big block, it became clear rather quickly that they werent going to be needed any more. there were no vacuum lines connected to these boxes... only the 3 wires each. if these 2 boxes were the "computer", they were pretty archaic, and they worked without knowing what the engine was doing.
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