DFIS with Accell coil
 

Would it be possible to use an Accell ecoil with dual outlet high voltage terminals to get DFIS on a 1979 RX-7?
This would be a wasted spark system for the leading plugs.
Could the j109 on the '81-85 electronic distributor be used to trigger this?
If not, could the distributor pickup be wired to a GM HEI unit to fire the ecoil?
How does the 2GC coil compare to the Accell? Accell claims 45,000 volts with high energy transfer. IE low primary amps for full output.

you need an ignition box. i just stepped up to an msd box.... wooortthhh it :D

The Accel coil was designed for either inductive or capacitive discharge. Inductive will give a low voltage, long duration spark while CD will give a high voltage, short duration spark. The rotary prefers a long duration spark because of its long combustion chamber. Even so, people have had great results with CD boxes like the MSD when it's used in combination with a coil that was designed with CDI in mind ie the Accel DIS coil, or the MSD brand DIS coil that hyper4mance2k is using.

Or you could use an HEI ignition module. It will give you a long duration, lower voltage spark than a CDI box. The HEI module costs around $30. The MSD costs upwards of $100 or thereabouts. A new MSD 6AL costs around $200.

Accel wasted spark
 

Jeff20B If the J109 can fire the GM style Accel coil itseems that I would get the benefit of direct fire with short plug wires and no path through the distributor for the leading plugs. this should be a heafty upgrade from stock points and '80 or '81-'85 electronic systems. This would allow transferring the trailing to the leading terminals on the distributor improving the spark energy to the trailing as well. If this will work it looks like a $35 project with substantial benefits. I have a few responses that say to go high tech (and high buck) but even though some of the suggested methods may be somewhat better. It seems that a 40% improvement for $40 may make sense for a lot of folks on a "bang for the buck" basis rather than a 100% improvement for $400. Would it be possible for some of the folks who have test bench capability to put together a matrix of the various ignition upgradeswith a column for spark energy, volts and duration or dwell? This might help lots of us decide how to proceed and may show an incremental path to the "ultimate" system that would allow us to do just as much upgrade as our setup needs while not wasting resources on deadend efforts. To that end, has anyone triggered a GM style coil with a J109? What was the result?

The J-109 can only handle about 3 amps before it goes into 'current limiting mode'. A typical GM HEI will handle 5 or 6 amps before it starts to current limit. As you say, it's great to get a pretty good improvement for very little money, and it can be accomplished on the rotary. I have my doubts as to whether the J-109 can handle the lower internal resistance and different inductance of an accel coil though. It was originaly designed with CDI in mind, but can probably work ok with inductive ignition as well.

You may be better off purchasing a GM HEI and triggereing the coil with it. Leave the J-109 completely out of the circuit. You can file down some male quick disconnects until they fit snugly into the holes of the female terminals of the distributor (where the J-109 would normally sit). I've done this on several projects and the terminals never fall out. I can provide a picture or two if needed.

please do, jeff.

It just started raining here. I'll get the pictures up... eventually.

J109 current limit
 

Jeff20B
This raises another thought.
Why not run a ballast resistor in the coil primary as the '71 and up MOPARS do to limit the primary current to 3 amps? This would only add about $2 to the program.

I adopted a philosophy of never using a ballast resistor. I basically didn't like what it represented; current limiting. If the vehicle came stock with one, I'd leave it there, but I could never add one during an ignition upgrade, as strange as it may sound.

Here you go.
https://www.rx7club.com/forum/attach...d=134778&stc=1

https://www.rx7club.com/forum/attach...d=134779&stc=1

which hei ignition module is this? accel? part number?

There are two types. Four pin or seven pin. There may even be an eight pin. All you need is the four pin version. Ask for an ignition module for a '79 Corvette or something. Can anybody else confirm?

'85 electronic distributor is on the way. 2gen Fuse box on hand to relocate fusible links box. Accel dual outlet coil ordered from Summit. I will do some bench testing to see what is needed to keep primary current within the limits of the J109. "Film at 11:00 pm" IE I will post outcome.

ballast resistors
 

Jeff20B:
I can relate to that! When I converted my tractor from 6 volt positive to 12 volt negative I went to dual field alternator with electronic voltage regulator and a Pertronix electronic distributor conversion with the vibration tolerant coil with internal resistance such that the ballast resistor was not needed. works great!
Dennis L. Cote

That's great! The next mod on your list should be to throw a 13B in that thing. :D In all seriousness, all you'd need to do is gear it to keep the 13B in its torque peak and you'd plow that field in no time! Heck, even a 12A.

'85 distributor is here!
Still waiting for the coil.
Should be here by the end of the week.

Cool...

Coil is here! Primary resistance is 1 ohm while the stock coil is 1.5 ohm.
Kevin Wright's page on electronic distibutor into '79 suggests eliminating the ballast resistors.
It appears that 1.5 or 2.0 ohms of ballast would keep the primary current to the coil at about the 3 amp level. Does anyone know what the output voltage of the J109 is?

12V if I'm not mistaken...

Compareing the '85 12A ignition schematic to the '79 it appears thJi09 may not have an "output " as such, but rather that it momentarily grounds the - side of the coil to create the magnetic field. When the field collapses the coil fires.
I suspect that this limits the time the current is actually flowing to just the "dwell" needed and this then eliminates the need for ballast resistors on the stock setup. It is not clear to me yet if the 1 ohm primary resistance of the Acell coil is requires a 1 - 1.5 ohm ballast to prevent over current through the J109. It appears that I could use one of the stock ballast resistors to accomplish the current limiting.
Any thoughts?

distributor cap
 

I finished the cap for the full direct fire scheme.
coil mount is next.

https://www.rx7club.com/attachment.p...hmentid=104149
https://www.rx7club.com/attachment.p...hmentid=104150

great threads to read!!

https://www.rx7club.com/showthread.p...4&page=2&pp=40

https://www.rx7club.com/showthread.p...hlight=msd+dis