mazdoo

You would have to make a bracket from the trailing top left sensor to suspend an additional sensor 45 from it. I have a dizzy setup to direct fire both leading and direct fire each trailing individually just wanted to get it done in a cas.

Rx7carl

YARRRRRR GENIUS!!!!!!!!!!!!!!!!!!!!! So how do you actually do the rest? 4 MSD's? 4 igniters? This wouldnt get you a wasted spark would it? but who cares!

Jeff20B

iTrader: (13)

It wouldn't.

I did something even greater for a 20B. It had three pickups on the bottom with a stock 4 tooth reluctor for the so called wasted spark on leading (technically it's not wasted spark on a 20B but you know what I mean), and three pickups on the top with a 2 tooth reluctor for single firing trailing.

Trailing wasn't worth the effort so I only test ran the 20B on leading only. It worked fine. Three pickups, three ignitors, three coils, three plug wires, three spark plugs. NA, obviously.

My next task is a 4 rotor with wasted spark.

Hades12

elwood Built what you see there, Right now it is in a Bag in a Box in my shead, The plan is 4 GM HEI, or a COP setup.

Jeff20B

iTrader: (13)

That will work but do me a favor. Try to pull both reluctors and install a stock 4 tooth at the bottom and a 2 tooth at the top. You'll get the nice simultaneously fired ignition on leading and single fired trailing.

Rub20B

Bringing back from the past.

Jeff, when doing this, one would get 'wasted spark' on the leading, so the leading coils would fire the double amount than with the 2 tooth wheel. now the question is: what does the engine like the most? less load and heat on the coil (as it need to fire only half as mch with 2 tooth wheel), or a very late leading (wasted) spark 180 deg after the 'normal' near tdc leading spark when the downside that the coil and plug needs to first twice as much...

Jeff20B

iTrader: (13)

The coil is firing its normal amount when it sparks twice per revolution, as in wasted spark or stock through the cap. The only difference here is wasted spark uses two coils for leading and through the cap uses one coil for leading. It (they) still spark twice per revolution as the Mazda engineers intended. This means you can use an aftermarket tach set to 4cyl mode and it reads correctly.

This is all for leading only. Don't get confused and try to factor in trailing. I mention this disclaimer because the thread topic is about trailing etc.

Rub20B

Sure, but with 2 instead of 4 bump the leading works just like the trailing, so the coils only fire half the rate, and thus have twice the time for loading, which might be a good thing at 9500 rpm??

Jeff20B

iTrader: (13)

Yep, it might be a good thing at really high RPM.

doogy2

iTrader: (2)

or just get rid of the trailing alltogethere

doogy2

iTrader: (2)

ran out of gas but yes it runs good

https://www.facebook.com/photo.php?v=10200331764956755

ArmyOfOne

iTrader: (12)

I did something like this using 2 msd 6al's, 2 2nd gen leading coils. It fired 1 coil set per rotor, no split. Car made real good n/a power. 225 from a BP 6port engine.

doogy2

iTrader: (2)

yes this is a 6 port too but i have the trailing blocked with plugs lets you advance the timing much more