Magneti Marelli AEC 301 ignition

Competition engines and ancillaries - general discussion
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achy
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Magneti Marelli AEC 301 ignition

Post by achy » Mon Oct 30, 2006 11:11 am

I have recently found an ignition set from Magneti Marelli with name AEC 301 electronic ignition. It consisted from a big tranzistorized unit and a high out put coil and is destined for 124. I have never seen such an animal but looks powerfull.
Does anybody knows details on this set and with what distrubutor type is working with : the contact breaker one or the electronic ?

Guy Croft
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Post by Guy Croft » Tue Nov 14, 2006 10:40 am

Let's have some high quality photos please Achy.

GC

achy
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Post by achy » Tue Nov 14, 2006 3:03 pm

OK Guy

Here they are

In general terms is a capacitive dishcharge system destined for powerfull short term spark.
The question is : is it possible such system to be used with the electronic distributor of Fiat.
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NickRP
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Post by NickRP » Tue Nov 14, 2006 5:50 pm

Hello Achy,

I do not have any expirience with that particular ignition system, but I will try to assist you in finding out how the system is supposed to be triggered. My first question is of course: do you have a wiring schematic for this setup (from there I might be able to make a positive identification of the trigger mechanism)? If not, you might want to source one?

All the best,
Nikola Radenkovic

1969race125
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Post by 1969race125 » Tue Nov 14, 2006 9:20 pm

It looks like you have transposed the numbers in your original post - the pictures show a 103, not a 301.

I'm not familiar with the "B" version, but the AEC 103 A "dinoplex" electronic ignition setup was widely used by Ferrari in Dino and other models, and was also used in the road-going Lancia Stratos. It originally used a mechanical distributor.

I'm afraid I do not know how the 103 B differs from the 103 A.

Andrew

Guy Croft
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Post by Guy Croft » Wed Nov 15, 2006 10:29 am

Well, I've seen packs like this before on 131 16v and 037.

Obviously the amplifier takes a signal from an electromagnetic trigger in the distributor, similar to the ones used on Bosch and Marelli electronic units in Beta and 131 models.

What governs how much current and what voltage you can put into a transistor unit like that? If you wired up the amp unit and coil and just hooked up a 131 type Bosch electronic distributor and spun it - what could go wrong in the amp unit?

GC

NickRP
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Post by NickRP » Wed Nov 15, 2006 10:52 am

Guy Croft wrote:If you wired up the amp unit and coil and just hooked up a 131 type Bosch electronic distributor and spun it - what could go wrong in the amp unit?
It is important to connect the amp unit to correct type of trigger. By type of trigger I mean: inductive, Hall or optical. If that is correct, there should be no damage to the amp unit when it is connected to non OEM trigger. Amp units are designed in that way that they have internal protection from overvoltage on trigger input (to list the simplest method, input resistor and diodes to Vcc and GND).

All the best,
Nikola Radenkovic

achy
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Post by achy » Wed Nov 15, 2006 11:36 am

Well I bought the set without a schematic diagramm but I found a 124 guy who had it and finally I acquired it.
The diagramm shows the device to be connected with mechanical distributor with one wire.
The difference between the two models A and B is that A is for 4/8 cylinder engines while B is for 2/4 ones.
The question remains : Is it possible to connect the AEC103 with the electronic distributor instead of mechanical and how ?
The electronic has two wires output while the mech has one.
I do not want to use points because I do not trust them in high rpm although I have a brand new mech distributor for 124CSA (S144 BA).
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Guy Croft
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Post by Guy Croft » Wed Nov 15, 2006 12:12 pm

If it's just a single wire from the coil then it is (I surmise) a contact-assisted system and not fully electronic. And I think I see a condenser on the side of the distr in the drawing that confirms this.

These were quite commonly available in the aftermarket in the late 70s.

All the F/L inductive distributors have a two cable output from the coil.

So I presume, perhaps that this one is triggered from the full contact-breaker switching current at 12v. The advantage of the amp unit is longer points life (no arcing) and better dwell (coil charge up) stability throughout the rpm range. So, yes, much better than standard coil/points-only. By the way, the notes seem to suggest that you cannot run a tacho off that coil, not an easy problem to surmount.

Don't take my word as absolute gospel, Achy, don't burn it out! I don't have this thing in front of me.

GC

NickRP
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Post by NickRP » Wed Nov 15, 2006 12:30 pm

Generally speaking, it is possible to use it with inductive type of distributor trigger, but you'll need extra electronic for that. First I would suggest that you try it (just for test) to connect it with points type distributror and verify if it works. Then, measure how much current is drawn by the amp module trigger input when the points are closed, and at which voltage the trigger wire is floating when the points are opened (you'll need high input impedance multimeter for that). Then let me know the outcome.

I am not sure why do you want to use this specific amp unit (taking into account that you do not want to go back to points), but that's not the question here, is it?

Best regards,
Nikola Radenkovic

achy
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Post by achy » Wed Nov 15, 2006 1:19 pm

Well there is a serious reason.
It is capacitive discharge device which - theoretically- gives much stronger spark than the normal inductive one from the electronic distributor. It gives a very strong short duration spark which cannot be affected by the fouling on the spark plug edges.
So in combination with the reliable (in high rpm) electronic distributor can give an excellent performance ignition system with complete and effective combustion of the mixture.

NickRP
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Post by NickRP » Wed Nov 15, 2006 1:35 pm

So, let's try to put it in action then! Looking forward to your measurements.

Best regards,
Nikola

Niels11
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Re: Magneti Marelli AEC 301 ignition

Post by Niels11 » Mon Apr 25, 2016 7:38 pm

Achy,

How are you?
I find I am having a habit of reviving old threads in this forum...
On this one: Did you finally install the AEC 301 unit in combination with a electronic distributor ? If so, what distributor did you use? Is this for the 124 Gr. 4 car? How did you connect the two wires of the distributor? What were the results in terms of increased performance / issues?

Best,

Niels
GC_12

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