EDIS reliability under extreme conditions?

[Minami Kotaro]

I don't doubt that it's a huge improvement over the standard stock setup, but did you go straight from a distributor setup to EDIS, or did you go to MS controlling spark through the distributor (with a trigger wheel) and then to EDIS.

I never had a trigger wheel controlling the distributor. I was using MS to control timing and trigger the Pertronix module in my 009.

[msoultan]

that's pretty slick. What is the minimum diameter of a wheel? The pulley's OD was about 1/2" or so greater than the ID of the Ford EDIS trigger wheel. I wonder if I could have just mounted the pulley on the indexing wheel and milled out the teeth on the pulley...

[FixItAgainTony]

My wheel was 106mm (~4.2") or so. I do not believe that it is too particular, but I have seen evidence that the iron / (gap + iron) ratio seen by the Vr sensor needs to be in some range - call it 30-70 % or so. The Ford wheels are 4.8mm / (4.8mm + 8.4mm) = ~36% (140mm / 5.6" wheel). The iron part should probably be a reasonable percentage (80-120% or so?) of the diameter of magnetic core on the Vr sensor. I set mine up to follow the EDIS iron / (iron + gap) ratio. Works fine. I see something like 3V AC cranking. The gap of the Vr sensor to the wheel plays a large part in output voltage.

EDIS has a built-in VR signal hysteresis - the Vr AC signal needs to be greater than 0.5V AC in order to "arm"
per the documentation here: http://www.megamanual.com/ms2/EDIS.htm
As long as there is enough signal to get the engine started, it will probably be fine - the signal increases with increasing RPM.

- Charles.

[MadMax78]

Interesting to read some different opinions on this subject. Still. I'll think I'll go with a dizzy for spark distribution and the MS/trigger wheel for timing. With a modern distributor I'm using (Mallory or 123 ignition) it should not be such a huge different with an EDIS setup, since the dizzies are basically new with only little play. However, still curious for experiences from someone who has actually run a trigger wheel controlled dizzy vs. EDIS.

[msoultan]

Interesting to read some different opinions on this subject. Still. I'll think I'll go with a dizzy for spark distribution and the MS/trigger wheel for timing. With a modern distributor I'm using (Mallory or 123 ignition) it should not be such a huge different with an EDIS setup, since the dizzies are basically new with only little play. However, still curious for experiences from someone who has actually run a trigger wheel controlled dizzy vs. EDIS.

Just so you know, any cam play will not have an effect on timing. Also, make sure you leave the mechanical/vacuum advance enabled as it will just help to keep the rotor aligned with the correct post.

Mike

[MadMax78]

Also, make sure you leave the mechanical/vacuum advance enabled as it will just help to keep the rotor aligned with the correct post.

Uh, is that true? The rotor is on a solid shaft which runs all the way through the dizzy. So the position of the rotor in relation to the cap does not change when the distributor advances. The rotor has a wide contact so it will always make contact with the right post. So the dizzy does not have to be connected to anything, it just needs to spin.

[msoultan]

Also, make sure you leave the mechanical/vacuum advance enabled as it will just help to keep the rotor aligned with the correct post.

Uh, is that true?

Oh, sorry about that - the vacuum advance makes no difference because it just moves the breaker plate, which obviously isn't being used - Sorry, my bad!

The rotor is on a solid shaft which runs all the way through the dizzy. So the position of the rotor in relation to the cap does not change when the distributor advances.

The mechanical advance will "reorient" the rotor, but that is ok.

Mike

[FixItAgainTony]

However, still curious for experiences from someone who has actually run a trigger wheel controlled dizzy vs. EDIS.

I have seen / helped set up both. By far the biggest advantage is going to crank based tach input. Depending on how much play there is on a camshaft driven distributor, the results can be quite dramatic. When running with crank based ignition control, the timing marks look like they are frozen in place with a timing light - no scatter / jumping at all.

- Charles.

[msoultan]

When running with crank based ignition control, the timing marks look like they are frozen in place with a timing light - no scatter / jumping at all.

Yeah, while I thought my compufire was pretty accurate, it's amazing how rock-steady the timing mark stays!

[MadMax78]

When running with crank based ignition control, the timing marks look like they are frozen in place with a timing light - no scatter / jumping at all.

Yeah, while I thought my compufire was pretty accurate, it's amazing how rock-steady the timing mark stays!

Cool, that's what I'm looking for.

Actually, recently I installed a 123 ignition dizzy on a jaguar xke 3.8. It also has a rock steady spark, no movement at all, when revs increase you can actually see it advance degree by degree. However, I'm running a Mallory unilite on my bus which frankly is quite poor at delivering a steady spark. I also looked at a 123 unit for my bus before, but they don't have suitable advance curves for my engine. So this will be a nice solution.

I just ordered all my Megasquirt parts yesterday, should receive it by the end of the week or so. I'll get a custom trigger wheel made as well and if I receive the stuff by Friday I'll start soldering by then.

[msoultan]

Right on! I'm working with someone else that is adding the MS to his bus. I'm going to use your wiring diagram for his setup to keep things really clean. If I notice anything out of the ordinary, I will definitely let you know.

[msoultan]

Here's a very neat trigger wheel idea:

http://www.shoptalkforums.com/viewtopic ... 375#956375