Hello folks. After having spent several days of searching the forums (here and elsewhere), I'm entirely confused as to how to wire my ignition setup properly. I bought the race car back in 2018. It's a 1979 SA22C race car. It had two MSD 6AL boxes (6AL not 6AL-anything, just 6AL), two horizontally mounted ignition coils and a newer (1982?) distributor with igniters (taller distributor cap and rotor). The car barely ran because of carburation issues. Anyway, I re-wired the car except for the ignition system which I left alone. I managed to run the car through two short road racing seasons although I felt that the car was woefully underpowered. Last year, I upgraded the ignition coils to oil filled MSD Blaster 2 coils and I mounted the coils upright. I ran the car for another two races. Earlier this month, I was in the process of checking ignition timing and one of the MSD Blaster 2 coils melted. The leading ignition on rotor 1 was spot on but the leading ignition on rotor 2 was all over the place (just pulsing quickly but nothing was lining up with the pulley marks). When I checked the trailing on either rotors, there was nothing, not even a pulse on the timing light. That's when I saw the coil smoking. The ignition wiring was a mess with plug wires bundled up along with the wires to the signal wires to the igniters. I figured that there was a lot of cross talk and inductance happening. I gutted the entire wiring mess and decided to re-wire the ignition system from scratch. I remounted the MSD boxes from the cockpit to the front left side strut tower in order to shorten the wiring to the igniters. I also bought two new MSD Blaster Solid State coils. I eliminated the crusty, stiff and old 8 foot long MSD harness along with the connectors. Now I only have two 10AWG silicone wires (red) from the cockpit mounted kill switch to the MSD heavy red + (one for each box) and connected the MSD heavy black (-) to freshly mounted chassis ground. I also put some EMI shielding on the wiring to the igniters and to the coils to play it safe. This is where I am confused as to how to wire the rest of the ignition. Unfortunately, I stupidly did not make notes of how the ignition wiring was set up prior to my ripping everything out (frustration had set in). I am also unsure about the correct wire positions on the igniters themselves since the car never had the "T" shaped factory connectors to them and I've been unable to find a photo showing the polarity. I found the wiring schematic (attached photo) from this forum but I'm confused as to how this will work since the MSD box is directly wired to the battery but no wire from the ignition switch to turn the MSD on or off. Aren't I supposed to feed 12v from the ignition switch to the box? I called MSD Tech Support and they said to follow the schematic on page 10 (see attached photo). If so, that would mean that the white wire from the MSD box connects to the (-) post of the igniter. But how would I wire the igniter, i.e. what about the (+) post on the igniter? I apologize for the overly long and rambling post and I thank you in advance. EDIT: I do not want to go direct fire at this point. I just want to run one MSD box for the leading and one MSD box for the trailing.

 

From what I can see on your photograph the 1982 dizzy does not have igniters, which should be fine. Page 10 in your MSD manual is showing wiring for a points style distributor, but your 1982 distributor uses hall effect sensors and a spinning metal wheel to generate magnetic signals that the igniter would take as a signal to fire the coil.

So I think you need to look up the diagram for installing the MSD to replace igniters and use a magnetic pickup signal not to work off of a points style distributor. In other words the MSD boxes are the igniters for the MSD coils and they'll take their signals from the 1982 distributor.



Regarding the 12 volts coming from the ignition switch, yes you need that. It doesn't provide actual power except as a signal to energize the MSD boxes and coils through the heavy gauge red and black wires.

 

With an MSD, there are two ways to wire them on an electronic ignition car - piggy back off of the factory spark box(s) (ignitor/ignitors) or let the MSD replace the factory spark boxes. The piggy back method is shown on the second illustration.

If you piggy back off the OE spark boxes you don't use the violet and green wires and you do use the Red and White wires.
If you replace the OE spark boxes you use the violet and green wires and skip the red and white wires.

As an alternative to running two MSDs you can just use one for the Leading side of the ignition and let the Trailing side use the OE ignition. This approach gives you a spare MSD box. The trailing ignition doesn't do much and putting an MSD on it is of little to no value.

Yes you should shield the wires that are transferring the signal to the MSD boxes and the coils either by using shielded wire or some other mechanism. The length of the wire run for the trigger and the coil isn't really an issue as long as they are shielded. A new MSD box comes with shielded/twisted wires for the Violet/Green harness.

I got my shielded wire from an aircraft supply house which consists of a twisted pair of wires inside a shielding jacket. The shielding jacket is grounded to the car.

Where you have them is fine but keeping them cool is important. So keep that in mind.

Since you have the 6AL, don't install a rev limit chip. Rev limiters are not good for a rotary. I have a 6A on my car.

 

Hello mustanghammer.
1) So if I piggyback off of the igniters (as per the second illustration in my initial post) I won't have to connect any other wires to each circuit? If so, there would be no way to turn off the MSD ignition unless I added a switch (please see my crude sketch). In my case, I have installed a kill switch which is required anyway.
2) And the power supply to the igniters would come solely from the MSD box (red and white wires) and not from any external source?
3) I have no idea which is the correct orientation for the igniter terminals since I don't have the factory connectors with factory color coded wires as a guide. Which one is the (+) and which one is the (-) as inferred by the schematic?
4) I've added shielding to the wires leading to the igniters and to the coils and I have soldered a ground wire to the braided shielding so that they are grounded to the chassis.
Thank you for your help

 

UPDATE: I believe that I've figured it out. I looked at the ignition schematic from the factory manual which I should have done from the beginning (DUH). Once I understood how the stock ignition system was supposed to be wired, I introduced the MSD schematic which essentially "cut" the stock ignition wiring in my crude sketch. I also figured out how to correctly wire the igniters (hall effect switches mounted on the distributor) based on the factory pin out diagrams. However, I don't completely trust myself given the recent confusion so feel free to chime in if I have overlooked anything. Thanks.

 

Looks like you have it figured out.

Are you using the factory ignition key to start the car or do you have a separate switch for the starter and the ignition?

Make sure the Ground for the MSD (the big black wire) is really good. Mine is connected to a 1/4 bolt that is welded to a cage pad and the battery ground it connected to a 3/8 weld nut that is welded to the car. MSDs and aftermarket spark boxes in general don't tolerate bad grounds for very long.

 

General question: is there any advantage to using the stock ignitors to signal the MSD versus the magnetic pickup from the dizzy?

 

Thank you mustanghammer. I just needed another set of eyes to look things over, especially since I did not want to blow up what is a $300 box (ea). I have a panel mounted ignition off/on/momentary start switch. Since I was rewiring the car, I threw out any and all of the old grounds including the old and corroded cable that was the starter/engine block chassis ground and replaced it with a shiny and new 1/2" braided strap. I also installed new 1/2" braided strap for redundant engine (front housing) to firewall chassis ground. I replaced both battery cables with new 2 awg ultra flexible welding wire along with new battery terminals and covers. All of the main chassis grounds and the battery negative cable were anchored onto the chassis (spots were wire brushed down to bare metal then new hole drilled) using new 3/8--16 nut and bolts with serrated washers. I will be adding additional chassis grounds as I continue rewiring especially for the MSD and shielded signal wires. I took the importance of proper grounding for granted and I believe a faulty ground led to my melting a newish ignition coil. I did a lot of research on wiring and I found this informative article on grounding. https://www.w8ji.com/negative_lead_to_battery.htm

 

Hi Toruki. I do not know enough to answer your question. I'm just using what came on the car. I'm sure that I can reconfigure everything and switch to the wasted spark system but I don't want to take any more time trying to figure things out since I have a race in two days. BTW, Mazda does refer to the hall effect sensors mounted in the distributor as "igniters" on the factory wiring schematic. I was initially confused myself when I started doing research.

 

Using the factory Ignitor + the MSD means there are two things that can fail and stop the car. On the other hand, if the MSD dies, you can still run the car on the ignitor by changing the wires around. So doing it that way is pretty sound when you think about it.

Is there a performance advantage to using just the magnetic pickup.....dunno. It is easier to do on most OE electronic ignitions but a little harder on a Mazda because of way the ignitors are connected. There are several threads on the site that discuss this for use with MSD's and GM HEI modules.

The previous owner of my car rewired the distributor to eliminate the leading ignitor back in 2000 or so. Then he wired the MSD accordingly and had it driving two coils. I later switched to use a single two pole coil for a wasted spark ignition. I am still using it that way with the same analog MSD box. Probably need to get a spare. Calling their tech support to see if the new digital boxes will work is on my to-do list.

 

Thanks and interesting. I had assumed that J10x --> MSD was adding a another potential (pun intended) failure point but your thinking is interesting, i.e. you've got options with a quick re-wire. And it goes the other way...if the J10x dies you can rewire for magnetic sense.

@mikevillena: Good luck with your race!

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I called MSD tech on Monday regarding the use of a Digital 6A box on my RX7. Per the tech person, the Digital 6A can replace an analog 6A and there is no need to define the number of cylinders because there is no Rev Limiter. I think what is confusing is that the documentation for the 6A also covers the 6AL which includes info regarding cylinder selection.

Any who.....I ordered a Digital 6A for my car.

 

That's great. I remember the instructions for the old 6AL mentioning cutting wires to configure the number of cylinders. BTW, I am also gobsmacked by your race car build.