Ok, I've been reading what I can find on the old dual dizzy 12a's and the opinions are varied. Too heavy and hard to start at temp are the only fairly consistent complaints. Now I know they have the 6mm apex and 12 side seals, but are the rotor housings the same inside? I know the ports are different, what I what to know is can you upgrade it? Meaning could you yake one and swap the rotors/e-shaft/flywheel from a newer 12a in? Or some similar combo to get rid of the old rotors, or are they a different size? I actually like the idea of using one with a direct fire ignition system if I could find a way to get out of the old rotors w/odd seals. What mods have you guys done to these motors?

 

All kinds of things can be done! What are you attempting to accomplish?

There are some changes in 12a generations. The old twin dizzy front plate takes a different water pump. You can put a single dizzy front cover on a twin dizzy front plate, but not the other way around. So depends if you are trying to keep the twin dizzy's.

The older end and center plates do not have the hardened surfaces of the newer 12a's and the housings are reported not to be as durable(mind you the carbon seals were more gentle on the housings).

I think a 13b s4 ignition sending unit could be modified into the leading dizzy and run it on a megasquirt for direct fire.

There are more tension bolts in the old twin dizzy. If you mix and match 12a generations you'll need to deal with that. The rotors/e-shaft/flywheel from a newer 12a will swap over

If you're getting parts from a newer 12a you may be better off rebuilding that and staying away from the older 12a stuff.

 

I just have/had an opportunity to pick up one, and thought it would make a cool project if I could overcome the issues. I have some spare 12a parts and thought it might be sweet with dual dizzys to wire up the leading direct fire like my 12a. Do a DLIDFIS type thing but with dual dizzys. I didn't know about the plates not being hardened like the other 12as. I was hoping maybe I could just take the rotating assembly out of a newre12a and swap it in, eliminating the 12 side seals and 6mm apex, put a matching flywheel on and be good to go and lighten it up to boot.

 

you make life difficult. keep it simple

 

That's what I've been told. I like a challenge and to learn new stuff, so you gotta ask, or do to learn.

One of my mottos=
K -keep
I -it
S -simple
S -stupid

 

the dual dizzy is like any points dizzy, a PIA only twice as bad. swap front cover and go single electronic.

 

I have a 12a twin dizzy im planning on building. But i like the stock rotors. 6mm carbon seals stock are great. they dont wear fast and are great for high rpm.

Is it possible to keep the twin dizzy and convert them to electronic instead of points?

 

There really isn't anything gained from a twin dizzy motor. If it is a top mount starter then it wont bolt up to later transmissions.


Nothing of the shelf, you would have to make all custom parts to do it.


-billy

 

I say go for it. Nothing to loose and lots of knowledge about Mazda's early engineering efforts to be gained.

 

I agree with Jeff, go with the twin dizzy's, they looks cool and are unique. And if you don't mind fiddling with things the Points are not that bad, just another step in your tune-up routine. Either way good luck man!!!

 

It's actually pretty easy to hook up an aftermarket ignition box like an MSD to points (the white wire). This would allow for easy direct fire (no need to route the output through the leading cap and rotor). And since rotaries don't require trailing ignition to run... you could have a twin dizzy points to MSD direct fire semi-distributorless ignition system. That would be very unique and a really long acronym.

 

how awesome does that sound... real awesome!

 

I am using a 80 dizzy (no ignitors) to MSD to 2nd gen coil - direct fire without trailing on the rx3. The dizzy cap is just there to keep the water out

I plan to play with a 2nd gen CAS to trigger the MSD and get rid of the dizzy all together here shortly.

-billy

 

Billy, That's exactly what I was talking to someone awhile back about doin! Jeezus I think it was. Trying to figure out how difficult it would be to do that on say a twin dizzy, with 2 CAS's and direct fire. It would be one very unique and super clean look. (If it could be done) I figured out right away that at least for now, that was way over my head to attempt, but I'm still planning on doing it at some point. Even if one of the CAS's was just a gutted shell for looks. Very unique, not to mention a fun challenge. I'll need to do a hell of alot more research on ignitions before I'm ready though I'm afraid. Alot of other "interesting" ideas to work on first. i'm certainly going to try to work out something to do with a twin dizzy though, I just love "old school" stuff. And I think those are unique and interesting too. Just not sure what I'll put it in. Guess I'll figure it out as I go. (like everything else) LOL!

 

no need to recreate the wheel son

 

Yes, you are right Mel, and wrong. I mean no need to mess with a good thing, or fix somethin that isn't broke. But where would we be if Wankel had just figured the piston engine would be just fine? Only way to make a discovery/find new information is to "go where no man has gone before" discover "the outer limits" hehehehehe.

 

but a rotary engine has been around for the past 40+ years and there are reasons why they dumped the dual dizzy and points ignition system. Mazda's R&D didnt spend bucko time and hours for nothing.

 

I see your logic, but if we use that to gauge by, Mazda dumped the 12a, and the 13b as well. They also changed the 12a after the 80 models, along with the intake etc. But it is more or less common knowledge that the earlier intakes flow better. But sticking to ignitions, far as I know, they have long since dumped the dizzy to right? CAS's now. There will always be something better, but that doesn't mean that there isn't a way to improve on a "classic". IMO