http://cgi.ebay.com/ebaymotors/Mazda...22955374QQrdZ1 This cars on Ebay but what really interested me is the ignition system. I've never seen a setup like it and was interested to see if anyone has done this before. Looks pretty staight forward. They are running the signal from the CAS to the MSD's and firing both coils direct fire, no split, looks simple but would like to see if anyone else has done this. And if anyone knows exactly how to wire this up. Ignition guru's tune in to this thread I would really like to try this out as soon as I figure out the wiring.

 

um... why does that look different from any 2nd gen ignition system besides the ones in europe?

 

because all second gens have it so the cas single is interpreted by the ecu and other inputs (airtemp/ coolent temp/ load etc) and then the modified signal is sent to ignitors/coils

much different

 

I would guess that you could take a CAS and lop off all but two teeth from the 24 tooth wheel to trigger one rotor and use the existing 2 tooth wheel to trigger the other. Doing this will give each MSD a 360* trigger signal. They'll each fire once per revolution. The teeth would need to be phased exactly every 90*. Each wheel having 2 teeth at 180* and the wheels phased 90* to each other. And I'm assuming the MSD could be triggered directly from the reluctors in the CAS.

 

Great 'guess' CLudwig! That is exactly how we have the carb'd race car wired.

 

I posted a question a while ago about trying a setup very similar to this. I was told that firing the plugs in the same chamber off the same coil will yield a very low spark energy. Any comments?

 

yes, but you could easily just run 4 msd coils, or something

 

Blind squirel finds a nut every once in a while.

 

I don't see why? The coil is still firing 2 plugs as it was designed to.

Would the tacho still work on 4cyl mode with this setup??

 

But normally, it fires one of the plugs in an already combusted, low pressure situation. I'll try to find the post I made a while ago, the way it was explained to me makes sense.

 

https://www.rx7club.com/1st-generation-specific-1979-1985-18/second-gen-cas-pickup-firing-first-gen-ignitor-415097/

Ok there is my old thread. Just made me realize how long it's been since I've been home to work on my car. Depressing.

 

Odd, I had always heard that the guys running a zero or neg split can only do so under vacuum. And those are the Leading coil packs , so unless he's wired them to have 2 channels per coil pack, constant 0 split?

 

^They are running as zero timing split. You can run zero split under any load level. The total timing advance may or may not be different than one with splt though. Split affects this. Negative split can only be run under vacuum conditions and never at ambient or positive pressure.