Whizbang

At least Mazdatrix refers to it as the "Competition" dizzy since it's wired for external ignitors, however I recall issues with cross talk between the ignition circuits. Anyone have direct experience with either using the 1980 dizzy with MSD boxes (or other ignitors) or having this ignition cross talk issue? I feel like the way most MSD boxes are wired where the ignitors are gutted and the wires run along with each other works fine. This unit i have at least appears shielded.

j9fd3s

iTrader: (3)

the competition distributor, 4801-18-200 has only one pickup in it, with no advances. the signal goes to 2 x CDI boxes, one for leading and one for trailing, after that its "normal"

no cross talk if everything fires at the same time.

if you want to do more reading the search term is "inductive crossfire"

t_g_farrell

iTrader: (1)

The cross talk is only on the OEM setup where the weak 80 dizzy signal has to travel to the ignitors on the fender strut tower. I wonder if this has the better signal wheel found in the 81-85 dizzies?

mustanghammer

iTrader: (3)

I was getting "cross talk" and general ignition weirdness with my car until I installed a shielded/twisted pair wire from my MSD to the leading coil pack. It was causing my tach to jump around and an occasional high RPM miss. My buddy got the wire in bulk from an aircraft supply house. Anyway, all you have to ground shielding on one end of the wire and hook it as normal. Previously I has using a 14ga. non-shielded twisted pair wire and it just didn't work. BTW, MSDs come with a shield coil trigger wire.

FWIW, my car's leading signal is picked up from the distributor without using an igniter and wired directly to an MSD 6A. The MSD fires an MSD GM 2 pole coil pack for a wasted spark.

mikevillena

Hello mustanghammer. I am getting the same glitching on my tach. I am also running two MSD 6AL boxes. Would you mind sharing a schematic of how your ignition system is wired (if you have one handy)? I am planning on re-wiring the race car again this off season and will be moving the MSD boxes into the engine compartment where the battery currently sits. I will be relocating the battery to the right rear passenger well and will switch to a lighter AGM battery. Thank you.

j9fd3s

iTrader: (3)

interesting, RFI, Radio Frequency Interference

mustanghammer

iTrader: (3)

See the diagram below. This is how the wasted spark leading ignition on my car is wired. The MSD box replaces the Mazda igniter. I use an MSD 8224 Blaster coil instead of the canister coil in the diagram.

I used shielded wires to replace the orange/black wires that connects the MSD box to the Coil. I cannot remember if I used shielded wires on the green/violet wires that connect the MSD to the Magnetic pickup in the distributor. I will check this weekend when I go to the shop

I get the tach signal from the negative side of the trailing coil and not the MSD. I use it to run a Stewart Warner tach and a Summit Racing RPM switch (it activates a shift light).

mustanghammer

iTrader: (3)

Looked at the car today. I used twisted pair - grounded/shielded wire from the connection from the MSD to the magnetic pickup on the distributor. That is the green/violet wire in the diagram in the previous post. Note that this diagram only works if the Leading igniter isn't used.

Whizbang

What about instead of wasted spark, running the coil back to the dizzy per OE configuration and truly used the MSD box to replace the ignitor?

mustanghammer

iTrader: (3)

That can be done as well.

The wasted spark setup removes the leading circuit from the distributor cap/rotor which seems like a better deal to me especially at high RPMs. Plus it is fairly cheap because all you need is a dual pole coil and couple of spark plug wires. For coils, I have used ones made for Harley's and now for a GM passenger car.