It still is a series circuit. I don't know what is in the FBO box, but the ballast could have been moved into the box so the external one is no longer required. Regardless, the transistors and diodes in the box also have a voltage drop effect. So despite 12V at coil input, the ground terminal won't measure 0. There would be a voltage between 12 and 0 at the negative of the coil. The box drops that voltage to zero battery ground. There is now micro chip technology to control current flow to coil, but the old tech the current was set by the selection of the box, ballast and coil. But besides coil resistance, the inductance matters more. Determines how much current coil can handle, how fast it can charge. Wrong coil selection that charges too slow for the set current, would drop off in energy as rpm rises. Regardless of your dwell, you are firing a spark plug every 2.5msec at 6000 RPM engine speed with a V8 single coil. No time to charge coil with the old tech. Which by the way the MOPAR boxes had RPM limits around 5K for the HP BB 4spd cars. Think it was 5200 or 5400 for an automatic.

If you allow more current to flow the coil charges faster which is good for high rpm, but street driving the coil saturates too fast and overheats. Damage to coil. So it is all trade offs.

The GM system is mostly better because of the coil in my opinion. They could send more current to the coil all the time.

MSD is capacitive. Charge an Inductor (coil) in mill secs. Charge a capacitor in micro seconds. Hence MSD can discharge the required Voltage at much high rpms to get sufficient KV to the plug. It is a different process.

There are some really good tech articles on how much voltage and for what duration is required to jump the gap and ignite the mixture.

The other funny aspect especially with multi spark is that if the ignition misfires at normal fire time, if you look at how fast the piston is rotating at high RPM, the second spark to ignite mixture provides no useful power, just better emissions

Interesting thought. I run a plate that FBO makes that limits the advance on a Mopar distributor. You can set it wherever you want. I could go big on initial and set it up with only something like 10 degrees total mechanical. The vacuum advance adds 9 when in use.

the two FBO advance plates i have are very inaccurate.

It is very much trial by error. I also make sure to deburr them before using them as I have seen them hang up occasionally.

But having said all that, they are easy to use and change, I don't weld so welding the slots instead would be a challenge. I also think they work better on real Mopar distributors versus the current repros, the Mopar distributor weights are beefer and the axial play is less with the spring clip set up.

Just to add to this, the petronix setup has a fixed dwell of 22 degrees.

Will bee interesting to see if and how long that 40111 epoxy coil will last running no ballast resistor - Keep an eye on heat and stress cracks around the tower area

Ask me how I know

Did you try any other coils with your Mopar Performance Chrome ECU ?

Anyways


Don on his website clearly states
DO NOT use any MSD Blaster, Accell or parts store Coil, they are incorrect for the Micro-Processor Type FBO Ignition Box and will not perform correctly and will damage the ECU. The Processor has been programmed to maximize output to the 40011 coil. No other coil that we have tested will perform as well as the Pertronix 40011. The processor program is burned to match that coil. (We burn our programming to the processor in house)

Dragon slayer is 100% dead on with his details

All the ECUs I tested on the street - Trying to match the correct coil / ballast resistor in todays Chinese world is 90% the battle

Direct connection and Mopar Performance made it easy for us back in the 70s 80s and 90s

The Pertronix 40111 epoxy coil and FBO’s recommended oil filled pertronix 40011 coils are the same spec, so hopefully ok. I could just go with the oil filled. I did see a post elsewhere that FBO told another user they were the same.

With the Mopar chrome box and the JEGS box that I previously tried on this car I ran the Accel 8140. I have been running that Accel coil for some time, normally with an original Mopar orange box, on other cars. I paint them black before install. I would be interested with everyone’s take on the Accel coil.

As to the other boxes, China, etc.. To me, it looks like the Summit box and the lower priced Standard box are the same manufacturer based on the housing, paint, etc. I did take a Summit box apart, it was overall similar to the JEGs unit I dissected though it did actually run what looked like a heat shedding device inside the fake outside transistor, where the JEGS fake transistor cover was empty and just screwed on. Also the connector seemed more robust. Both used sand before potting. I did not take the higher priced Standard box apart, though I have those as spares.

As I mentioned, my 440 Challenger is running the blue JEGS box right now, and that is with the Accel 8140 coil. It does run really well (knock on wood) so I have left it alone. Here is the Challenger engine bay, yes I know I am crazy OCD on these. You can see the JEGS box on the upper passenger firewall.

Posts like this seem like debating:

“Should I use flint, chert, or michmetal alloy to set off the gunpowder in the flash pan of my Kentucky rifle”

For 30+ years automakers have spent their $ on
coil on plug ignitions and
special alloy tip sparkplugs like Irridium/Platinum.

Using two spark plugs per cylinder leads to less need for spark advance and less “negative work” due to cylinder pressures prior to top dead center.

Spark gap size
( Saab trying to jump a spark all the way to the piston crown)
and spark duration “burn time”
are widely accepted as more important than
peak flash over voltage
or multi-spark,
characteristics that aftermarket boxes alter.

Isn’t it
“Barking up the wrong tree”
to make efforts like cutting open aftermarket ignition boxes and examining how the epoxy potting looks?

To each his own.
I am not against spending money on whatever experiment gets you out of the easy chair and turning a wrench.

If you are really after performance using a Magnetic induction system has significant draw backs for high performance and high rpm. There is a reason a Capacitive Discharge system is chosen. Or the coil over plugs. If you only have to fire a coil once every revolution, the time to saturate the inductor is much greater by 8x, so even at 12000 rpm you have 4x more time or 10msec to charge the coil. Plenty of time.

Taking apart a bad box to examine not a waste in my opinion. We take everything else apart and mess with it.

Left is an Mopar black box 4111850 from late 70's I assume. Other probably a Standard product box. The Mopar is better constructed, heat and noise shielded with the board. Double grounded to case. Automotive standard. The other barely had the transistor heat sunk via friction, poor construction, and components with age issues. (Electrolic caps). Single ground. Different design too, but that could be an improvement or necessary for the power transistor.
'
The box sand should be a special silica for heat absorption and transfer along with protecting from environment. Whether the compound used meets a high standard???? Prestolite boxes I have seen never have the epoxy potting compound fail. The Mopar boxes do not age well. The compound on the SMP product wasn't full bound to the box. Most came out in hunks allowing the board to be removed easily. I guess you get what you pay for.

I understand you are right about the superiority of CD systems.

But, I have been through near a dozen Mopars over the years and have a locked in to sort of a routine with my cars that I am comfortable with. I look to bring the cars as close as possible to stock, certainly stock appearing. Electronically I bend on the integration of a Mopar ECU in to the stock engine harness to ditch the points. Early on I went with more aggressive builds but this is where I evolved to. I work on them, drive them around, do local cruises and the occasional show. To me the addition of a CD system is an escalation that I would rather not do, preferring to maximize performance stopping short of that. Hence the different type of Mopar style boxes and maybe Pertronix.

I have a bunch of NOS orange and chrome boxes that are original early 4 pin Mopar, even a couple of Standard 4 pin units from an old K-Mart still in their old dusty clamshell from hanging on a retail rack. But the Charger bends my rules above with the hotter build on the engine than stock, so I have been experimenting to see if there is better, but short of a CD system.

The introduction to the market of all the different Mopar style ECUs seems like the wild west with a lot of “less than robust” solutions out there. I tried the blue JEGS unit based on what our collective friend from Mopar Action recommends and sells on his e-bay store. The box does work well on my Challenger, I have been running it two years and it does seem to add a very slight positive change in the performance envelope when compared to the orange box. But I don’t think it is enough for the Hemi in my Charger, it didn’t get me where I want to go with the plugs/tuning.

**UPDATE**

A half a dozen trips in for test and tune, I am feeling hopeful and impressed.

I did feel confident enough after driving it a bit to alter the timing, changing the FBO plate in the distributor to limit the mechanical advance to 12 degrees. This allowed me to do 23 degrees initial and just short of 35 total mechanical at 2500 rpm (the vacuum can adds another 9).

Definitely idling better. Starting well. Pulls stronger, particularly at part throttle acceleration. I will keep messing with it, and see how it does as I drive it more…reliability, the coil as mentioned earlier, and so on.

My 383 / 432

N O S Chrysler 4111850 ECU
Correct Chrysler 3874767 Dual Ballast Resistor (.5 OHM)
Later versions where 1.2 OHM

Very nice!!!!

PM sent

Same with you - Beyond nice

Looks like where on the same page making these factory systems work in todays world
I went a little backwards finding factory original NOS electronics after testing just about everything available today where you are using what’s available now with better luck then I had

Great thread !

So as follow up, to update the string.

It has been four months with the FBO box on my Charger. I am enthusiastically thumbs up on the result. The car is running really well…plugs not fouled, starting easier, smoother idle. I have had the car out a bunch of times for cruises and shows and things have been smooth.

I do not think I will put one on my bone stock 440 Challenger which runs very well on just a standard Mopar ECU. But the Charger motor having the bigger cam, etc. had seemed to really need help and the FBO box was a very large improvement over an original Chrome box that I tried and the HiRev box from JEGS that I also looked at (and is successfully on my Challenger now).

I have, and have had the FBO box on my car for close to 20 years. Everything has been great after a few problems were corrected in the initial usage. The first distributor set up was not a good fit for my setup, but the second setup was perfect. The real issue I had was with the ballast. I had replaced my original wiring harness with one made by Evans (?). It had a 4 pin ballast connector, so I got a 4 pin ballast. We chased all kinds of issues from running great one second to nothing the next. Switched out distributors, changed plugs, set and reset the timing. I was at a show just outside Rochester and a fellow Moparts member solved my problem in a second. Tom Quadrini was looking at my car and asking questions. When I told him all the issues with the way it was running, he told me the ballast was the problem. The 4 pin was throwing off the resistance. When I switched to the 2 pin, the problem was solved.

X 2 on the cars coming in the shop

What would be helpful to know is how was it wired? Were you using the second ballast to the FBO box or was the issue of using the wrong resistor to the coil?

would a FBO box from 20yrs ago be the black box and not the newer box with the rev limiter? if so then it's basically a LX101 with an american made transistor. i used to have one and for the most part liked it.