EI, MMI vs Indigo?

[romantic comedy]

I have had my Atomic Four for 18 years now. It has always started with no problems. Since so many here just love the electronic ignition, I am thinking of getting it.

I would love to hear thoughts on the MMI electronic ignition compared to the Indigo electronic ignition.....please, help me decide.
Of course, I am leaning heavily on the MMI offering.

[Mo]

I really don't have much experience with EI. I have it installed on my boat but was also quiet comfortable and happy with the performance of the points and condenser.

EI, to me, just means a little less maintenance, and of course, generally are more trouble free. Keep in mind the correct coil resistance, and likely an external resister, needs to be installed as well.

I've only had my boat since 2007 and her first full summer in the water was 2008. Up until 2 years ago I used points and condenser...only once did I have an ignition issue which turned out to be a failed condenser. Took me about 20 minutes to figure that out and replace it.

Happy with the performance of the points and condenser, it was with coaxing from Dave Neptune that, I took the EI off my spare engine and put it on the boat engine. At that time I the coil and external resistor off the spare engine came as well. That has worked flawlessly since and have run the engine many times up to 4 to 6 hrs continuously on a number of occasions without an issue. I do believe the one currently on my boat is a pertronix ignitor and if I'm not mistaken that's what MMI sells.

[hanleyclifford]

EI offers the most advantage to those with difficult or cramped access to the distributor, but I made the switch because I couldn't get satisfactory dwell without reducing point gap to as low as .008" on my best distributor cam - the thing was just plumb worn out. Since installing the EI from Moyer Marine I have had much easier starting and no trouble. I check the dwell once in a while (residual OCD) and have installed a voltmeter to keep an eye on coil+.

[ndutton]

All three (points, Pertronix aka MMI and Indigo) strive to achieve the same goal, charging and discharging the coil. Points does it by a mechanical switch activated by a four lobe cam, Pertronix does it by a Hall Effect sensor (essentially non-contact magnetics) and Indigo does it via non-contact optics.

Dave's the guy to report on the Indigo with his many years of experience with it. We have studied and tested the Pertronix system on this forum and feel we have a pretty good handle on it. I'd suggest the biggest difference between Indigo and Pertronix is support in the event of problems. In practical terms your support with Indigo is Indigo, with Pertronix it's NOT Pertronix (see next paragraph) but rather the MMI forum.

Early in the EI studies we received some very contradictory advice from the Pertronix support desk, even from the same guy on the same day. The A-4 is a tiny niche market in Pertronix's customer base and therefore IMO their technical support staff doesn't often deal with our 4 cylinder low RPM engines. It's not an engineering or design problem, the Pertronix system functions great.

The work we did was based on Pertronix's own maximum amperage specification. Once that specification was followed religiously the reports of coil issues disappeared. Note that following our studies Indigo embraced the same protection for their optic EI system going as far as introducing a new product as a result.

There's another EI system available that at least one of our forum members is running on his engine, the Hot Spark. It's a Hall Effect system like Pertronix.

[Dave Neptune]

Go 4 the EI

As Neil states the points, magnetic or optical triggers (switches) are nothing more that an off/on switch.

I was a bit of a performance mechanic before I got my A-4 31 years ago. The engine was seized and The C adv did not work. I got the engine started finally without the c-adv and that was good enough to get it to Long Beach from Oxnard. Once here I pulled the distributor and took it to work. I had been Installing many an Allison Photo Optic ignitions on primarily "Rotaries" at that time. I simply made an adaptor and wired it in for the Allison. I ran it for about 20 years and when a similar one became available as a kit I bought it. I like the photo as it is at least a bit easier to install and trouble shoot, perhaps because of my familiarity with them. There is nothing better or worse in either one as they are both quality switches.

My engine is stock with the 35amp alt and I ran without a resistor on both the Allison and the Indigo (about 8 years) using the "flamethrower" coil with no issues. Most all of my motoring is in 5~6 hour runs to Catalina in the am before any wind has built, the wife likes to wake as we arrive. I never use any kind of a resistor and as most of the regulars on this forum know I have never broke down!! I was contacted by the competition to see if I would test the resistor for him. I did and what we were checking on was wether or not the resistor and reduced voltage had any influence on starting cold. As of this time a few years later I still don't notice that the resistor is there~can't hurt so it's still there. I also run the stock cold plugs for about 3 years or so and the same coil.

Dave Neptune

Most of the failures we see in the coils are associated with raised charging voltages and the ignition being left "ON" if the engine stalls.

[thatch]

Pro's and Con's

R C, I consider the change to EI to be a "no brainer", at least for me. On several occasions before adding the Pertronix (Moyer) unit, I would have to clean the points to get my A4 to fire. I attribute this to DBS (damp bilge syndrome). Since making the change the engine starts quicker and the timing has remained rock solid. I have a second EI unit on my test A4 that came from another company in Texas that seems to be a copy of the Pertronix unit that also has performed flawlessly. Of the 3 EI's available, the Indigo unit is probably the most high tech but at a higher price. It also has a control unit which has to be mounted seperately, which makes the installation a little more involved.
Tom

[romantic comedy]

Thanks guys. I am very familar with points and electronic ignition. So I understand the theory and all that.

I am just curious about the differences between the two. (Now it looks like there are three systems.)

If the EI is really just replacing the points, MMI makes sense. It seems pretty simple. With Indigo there is an extra box. Why is that? Does it help get a hotter spark in some different way then the MMI system? An extra box is something else to break.

[joe_db]

Both of them had issues before the ballast resistors were required.
AFAIK they both work fine now.

MSD also makes ignition systems that can be triggered by the Moyer system.

[Dave Neptune]

Ei

Joe, my Allison worked for about 18 years and the Indigo for at least 9 before I tried the resistor for Indigo to check on cold starts. This is with a "stock" charging system. Note, the Allison and the Indigo were both manufactured by the same company.

Dave Neptune

[romantic comedy]

What is the box with the Indigo EI. I assume MMi does not have one.

[Dave Neptune]

Magic box

The box is the electronics and the led indicator for the ignition firing, handy for quick checks. The photo cell is the only electrical in the distributor, a two wire lead. There is a "shutter", a plastic disc that snaps on the "cam". The disc has grooves or windows in it that the photo cell "see's" to time the ignition.

Dave Neptune

[joe_db]

I had endless issues with my Indigo. It was burning out coils at a rate of 1-2 a year.
This was prior to the ballast issue being known. I would not use one absent that resistor now. Not only does Indigo supply a resistor, but the source company (Crane Cams) supplies one as well for their car units. I do not know if Pertronix ever followed up on the forum research or if Moyer is the only place suggesting a resistor for the Pertronix.

I am thinking my ultimare setup is going to be Pertronix firing an MSD 6

[Dave Neptune]

EI all the way

I used my Indigo for 9 years at over 100 hours a season, in 5&6 hour chunks and I never had a coil burn out or any fouling or stalling with no resistor. They are both good units and work fine. And I have a stock alt and regulator which peaks around 13.8 volts so I don't have the elevated charging we have seen to be a big problem with EI's in general due to the extended dwell. I have used many a photo ignition over the years and because I am familiar with them I chose that style of "switch". I do like having the led trigger indicator for confirmation of function though.

Yes that's 30 years of EI and no resistor AND now 1 year with as a favor to Tom. He was interested in cold starting and thought I could give him some good feedback. I have noticed no cold starting issues even with weak batteries doing the starting.

Dave Neptune

[joe_db]

My running voltage is over 14 or my big batteries would never charge. I think that is a large part of my appetite for coils back in the day.
As you can see, the source of the Indigo unit apparently assumed there would be a ballast resistor. This obviously was not always true.

I used my Indigo for 9 years at over 100 hours a season, in 5&6 hour chunks and I never had a coil burn out or any fouling or stalling with no resistor. They are both good units and work fine. And I have a stock alt and regulator which peaks around 13.8 volts so I don't have the elevated charging we have seen to be a big problem with EI's in general due to the extended dwell. I have used many a photo ignition over the years and because I am familiar with them I chose that style of "switch". I do like having the led trigger indicator for confirmation of function though.

Yes that's 30 years of EI and no resistor AND now 1 year with as a favor to Tom. He was interested in cold starting and thought I could give him some good feedback. I have noticed no cold starting issues even with weak batteries doing the starting.

Dave Neptune

[ndutton]

I agree with you Joe. Big alternator output in volts calculates to more amperage than the system can handle long term. Another factor we can't do a lick about is coil saturation with the added dwell of EI which makes the amperage factor all the more important.

Dave is running with a comparatively tame original Motorola alternator with (I'm guessing) around 13.8V output.