Dual MSD 6AL Installation.
 

Im going to be installing two 6al boxes. one for leading one for trailing. I was just wondering if anyone has a diagram or some advice. I'm prettyy knowledgeable about wiring but ive read on here while trying to search, that if i connect the trailing one up post igniter that i will grenade my motor due to residual spark from the leading ignition?

So what im getting is that i should connect my leading post igniter, and on the trailing i should bypass the igniter. is this correct also what color are the wires i need to connect the msd to on the input side for both leading and trailing?

Thanks!

you can bypass both ignitors and use the magnetic pickup inside the dizzy. The msd boxes have a green and purple wires. Use those to connect to the dizzy. Idk what color goes to wich though. You can run just the leading if ur worried about grennading ur motor. And if you just run leading you can advance the timing more.

you need two boxes for trailing alone. I recommend you either use one for leading, or find a way to convert leading to direct fire and do away with wastespark, driving each leading coil with its own box and not waste time using a box on the trailing.

The latter is what I did but I have a haltech and I don't know how you'd do that with a dizzy. Easiest is to use one box on your leading. Boxes on trailing are a waste of time.

I've heard this is a great set up using one 6AL for DLIDFIS. Havn't tried myself though.

http://www.mazspeed.com/msd.htm

i want two boxes so i can run a rev limiter. the wires are orange black red and white i believe. i know my boxes do not have a green or purple wire. and why does everyone keep saying that i need to run two boxes just for trailing? there isnt two ignition for trailing now?

yeah with the distributor, you run one box for leading and one for trailing. have you looked at the MSD website? they have a couple of diagrams.

MSD boxes can use either the magnetic pickup signal, via the green and purple wires, or the stock ignitors, via the um other two trigger wires (orange and black? blue? i forget)

I used the directions on the MSD site, page 40-42 of the online manual. I'm using the stock ignitors as an amplifer for the MSD box. I only have it running the leading right now but I will be installing a second box for the trailing. I have my spark going through the cap and rotor still. Did a dyno comparison and the dual coil leading did nothing in the top end which is where my motor make power.

I have looked at the msd diagram and that is how i planned on running it with two boxes. but ive read some stuff about that not working and supposedly needing two boxes for trailing and all that nonsense. if it is nonsense indeed i dont know. thats what im trying to figure out. also if i can bypass the igniters is that better or worse. the way i figure, if i bypass them its one less thing to fail? any thoughts? also if i do bypass them which color do i hook to the leading box input pos/neg and same with trailing?


thanks again for all your input guys!

for the NON distributor cars you need 3 boxes. on the EFI cars they use whats called a 3 channel ignition, the leadings are shared, 1 box. the trailings are separate T1 and T2, and thus require 2 more boxes.

the distributor ignition, is 2, leading and trailing. the cap and rotor chose #1 rotor or #2 rotor.

i'm running the ignitor with mine, if the MSD fails, its very simple to bypass.

in theory though the ignitor adds another thing to fail (dizzy+ msd is simpler than dizzy+ignitor+msd).

the ignitor vs magnetic pickup take different wires, i had no trouble finding which ones, you just need to decide to use the ignitor or not

got it all wired up... two boxes one for leading one for trailing. still using the ignitors. 7200 rev limit on both boxes. when floored it revs to about 7400 on the stock tach. it backfires like a mother. kinda sweet but im not sure if this is normal. im thinking it is for a rotary due to the inefficiency of the engine and the raw fuel thats not getting burned and going into the exhaust and then getting ignited from the next combustion event when the msd gives it spark again. i will have to post up some pictures here soon. so you guys can let me know what you think...

here is where i am so far... no wire loom yet. i cleaned a ton of wires and made some new harnesses that are shorter. ill get new pics up in my albums soon. im pretty pleased with it so far. lt me know what you think...

backfires are normal. when you turn off the ignition, there is suddenly a LOT of leftover fuel to get ignited when the ignition turns on....

also the tach being a little off is normal, they are pretty accurate in the 1000-4000 range you use all the time, but they speed up as you pass 6000...

sweet i wasnt super worried about the backfires but thanks now im not at all.
I kinda figured that the revs are so high that it maybe just cut out at 7200 but revved a little higher but i guess the tach being off makes more sense.

thanks again

Just want to say for the record and incase any newbs go searching in the future that I was wrong on the MSD boxes. I'm right about EFI boxes, but didn't know dizzy's had different spark arrangements.

My bad, should have shut up.

Think christmas

Dizzy red to MSD green
Dizzy green to MSD purple

So now that you have it installed, how do you like it? I'm running two Mallory boxes and coils and all I can say is thet I have a lot more low end power and it idles as smooth as silk. It is an expensive mod but WELL worth it in my opinion..

you should setup a Direct Fire with those two boxes and leave the trailing stock, the rev limiters will still work for the most part whan I had mine setup this way. when the leading msd boxes hit redline only the trailing would fire and there would be almost no power, but it also makes it so there is no back firing.

You will notice a huge diffrence if you run dual msd box direct fire:nod:

I am going to be running a turbo on this setup... is directfire still wise with only having a rev limit on the leading?

Yes it run a but better. Mostly i did this so i have better spark when i get my turbo done here in a few weeks.