Hi everyone, I'm currently trying to get my car running, it's a 1993 Miata with a 1983 12a in it. I plan on doing the MSD 6al ignition setup just like Scott M. Baker (https://www.smbaker.com/sand-rail/ma...-rotary-engine). My main reason for doing this is for the feature of adding a rev limiter. My only question is, would only running the 6al/rev limiter on the leading side and not the trailing side cause the rev limiter to not work? Like could the trailing side spark keep revving up the engine without the leading side?
Thank you for any feedback.

 

Here's a relevant thread about running just on trailing, which is essentially what you are talking about when you rev limit the leading, I think.

https://www.rx7club.com/2nd-generati...ioning-235893/

 

I recommend that you just run an MSD 6A Digital on the leading side and use the stock ignition on the the trailing. Rotaries don't need a rev limiter and there has been evidence that rev limiters like the kind employed by MSD can do damage. https://www.rx7club.com/race-car-tec...miter-1093845/

If you are concerned about an over-rev, get a shift light. I use one in my race car and it really gets my attention.

 

Note that using a rev limiter on a rotary under load will cause mechanical damage. They do not tolerate the stuttering misfires while under load. It breaks apex seals and stationary gears. 12As are especially vulnerable because they have breakage prone 3mm apex seals.

Using a 2 step is okay because the engine isn't loaded.

I used to use a 6AL with a 2 step box for a flat shift. I had a 6000rpm pill and an open circuit. No rev limiter, just a 6000rpm limit with the clutch depressed.

 

Any one has a wiring diagram when using 2 MSD 6Al and - boxes of 2-step on a carb 12a?

I need full wiring instructions in order to take it to get done. Most shops around me only work on cars with computers, efi and turbo.

 

I don't think you can run 1 6AL box on the trailing, I believe you need to run two of them. I ditched trailing completely on mine.

Used MSD 6a, no clue on MSD 6AL. The difference between the two I believe is which wires you cut. https://www.rx7club.com/1st-generati...ked-up-833320/

Thats my thread hooking it up. No pictures but I remember a bunch. I have a video of it starting with no plug wires in the dizzy at all.

Used electronic dizzy not points.
Gutted J109 ignitor on leading. After gutting you are left with 2 tabs side by side on the top and 2 tabs beside each other on the right. You need to hook them up like so:

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Wire it up like in MSD diagram for Magnetic Pickup (MSD Green/Violet).

I never ran trailing, but if you find a way to ground the WHITE wire while using the G/V wire, you will stop that box's ignition. I could see something like tapping the ign cut circuit on the 6AL with a relayed ground to both MSD 6A trailing boxes white wires. Dirty but "theoretically" possible.

I ditched my trailing completely. Used threaded rod to make an insert in the trailing plugs to hold a laser'd bracket that held my 2nd coils on. I don't remember the pitch exactly but I did use engine dowels as spacers and the SA lug bolts are the same thread pitch. Don't ask

 

Still working on it, the reason to have 2 6Al boxes is that one will be connected to leading and the 2nd box to trailing. Not only do you get a more powerful spark to both but you also get to choose what top rpm cut-off you want. By adding 2 boxes of 2step now you also get to pick a lower rpm when ever you hit the switch or clutch.

The problem is both coils are connected to the 6Al boxes, no way in shutting of the negative on the trailing coil.

Not sure how it would work just shutting down completely the 6Al box connected to the trailing coil while hitting the switch or clutch , 1 problem is you eliminate the top rpm limiter which isn't good

 

Yes but you cannot run 1 MSD 6AL on the trailing. You can one leading MSD 6AL because dual fire but trailing gets each their own. You want to run one on trailing you will get direct fire and your gonna have a bad time lol.

 

I wrote this on a FB page as others were also looking for the same info

So my MSD wiring is done. For those running dual MSD 6Al boxes and dual 2step boxes you can't add a relay to the trailing coil once the 6Al is connected to both coils. There is no way to interrupt the signal. The reason why we use 2 6Al boxes (is for safety) is so that you can choose what top rev limiter you want to cut on both coils at the same time. Thanks to Jorge Cofresi owner of JSwiring and Performance in Winter Haven (he also did my motor) was able to wire a relay in order to shut off the trailing 6Al completely while hitting the switch for the 2step. While the 2step wire works with power he was able to wire it were the negative of the 6Al box is cut off. So now I get pops & flames when hitting my 2step all while only being at 3500 rpm's and still having my top limiter on both coils set at 8400 rpm's

In other words this will:

give pops & flames at 3500 rpm by using 2step when hitting a switch (for show)

top limiter will still work on both coils at all times, at whatever rpm you set it up to, nothing needed for it to work. Just smash the gas pedal all the way down. (for safety)

On a side note, the older 6Al boxes and 2step boxes with the pill module's are preferred over the new digital 6Al boxes. The new boxes sometimes has trouble reading the signals given on rotary ignition. Sometimes it works and sometimes it doesn't. Because of that info I purchased all my msd item used on FB market place. They can be easily found as many are turning on to computers and efi systems.

 

This is set at 3000 rpm, no need to rev pass 7000 rpm and just kill the engine

 

When I had a RB Dellorto on my SA, it shot flames and backfires whenever I let it load up on coasting and then let off the gas. It was a lot easier and cheaper and required no extra wiring.

 

But MSD is on demand, don't even have to drive the car.