Use of a distributor

crab · Post by **crab** » Sat May 17, 2008 4:34 pm

Is it possible to use a distributor (purley to distribute the spark to the correct cylinder) rather than using ford coil packs. I intend to use a Megajolt unit in an Alfa Giulia GTA replica and would like to keep the distibutor for origonality.
Steve
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Ferrari 333 SP history

Post by **brentp** » Sat May 17, 2008 5:41 pm

Since the crank fired system uses multiple coil packs, compared to the distributor's system one coil pack, this would be very difficult to accomplish.

If you haven't installed the system yet you may come to the conclusion after installation that your engine run so much better you won't care about the look. Perhaps you could explain to people that is what the factory would've done if the technology was available?

esv · Post by **esv** » Sun May 18, 2008 2:27 pm

Just a thought, from the top of my head:

The Ford EDIS black box fires two coils alternately, via two cables. What would happen if both the two output wires from the black box were connected to a single coil? Would this coil fire on every signal (so could be routed to correct cylinder via rotor), would the coil fail to fire, or would the black box get confused and / or die?

Dimbit · Post by **Dimbit** » Sun May 18, 2008 2:29 pm

That might run into problems at high rpm when one coil may be charging as the other fires.

alexander · Post by **alexander** » Mon May 19, 2008 12:37 am

Dimbit wrote:That might run into problems at high rpm when one coil may be charging as the other fires.

i think esv is suggesting using just one coil ie sending both trigger signals to one coil. sounds to me like it would work... interesting idea!

cheers

Dimbit · Post by **Dimbit** » Mon May 19, 2008 6:23 am

alexander wrote: i think esv is suggesting using just one coil ie sending both trigger signals to one coil. sounds to me like it would work... interesting idea!
cheers

Yes. As I said, that might run into problems at high rpm when one coil may be charging as the other fires.

crab · Post by **crab** » Mon May 19, 2008 5:27 pm

hello, if the wires from the coil to the EIDS unit go the 0v and the coil is fired by breaking this circuit, by connecting both wires to one coil would mean as one circuit switchs the other circiut would still have a path to 0v and the coil would not spark
Steve
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lolol

esv · Post by **esv** » Wed May 21, 2008 5:10 pm

That might be a problem, but depends on the "opening time" of the EDIS. The actial spark discharge takes very little time, so there would be no need for the EDIS to ground the coil voltage for longer than necessary. (This is the equivalent of dwell angle for a distributor, I guess.) But I don't know how the EDIS behaves, so it would need an actual experiment.

alexander · Post by **alexander** » Wed May 21, 2008 11:46 pm

so the problem is that we have two EDIS wires connected to one coil, both of which spend most of their time at +12v. so when one goes to 0v, in addition to making the coil fire, it would also cause a dead short between the EDIS wires.

so what if a diode is put in each EDIS wire, allowing the coil primary to discharge through it when it goes to 0v, but stops current flowing the other way when it is +12v, and the other EDIS wire goes low?

so then you have a spark event every half engine cycle, and the EDIS wires are isolated from each other.

alexander.