We are converting a Li'l Red to run off of a FiTech with timing control. The truck has an aftermarket MSD coil and I would like to bypass the factory 4-pin ballast while maintaining a factory look.

What is the purpose of the 4-pin vs the 2-pin?

I would like to just gut the four wire and put solid wires on the backside to bypass it.

2 ballast pins ( anything between .5 and 1,5 ohms )is to feed the coil accordingly with temp and load changes without need to feed the full 12 volts, keeping it safe from overheat

4 ballast pin gets an extra source to feed the 5 pins ECUs with an aux resistor ( around 4.5 to 5.5 ohms ) through the green traced red wire.

later the 5 pins ECU was changed to 4 pins. The axiliary resistor was moved into the ECU assembly so no need anymore for a 4 prongs Ballast, but back to to 2 prongs, but 4 prongs can be used thought, just the aux resistor won't be getting any load on it


factory look and still bypass the resistor on the clean look:
You can remove the epoxy of the ceramic groove on back and replace the resistor with a jumper wire ( 14 gauge is way enough ) reusing the ceramic prongs attached to resistor. Done. Isolate the ends of the wire/terminals on ceramic groove with epoxy back for safety



You also can simply add a jumper wire between prongs ( using spade terminal splitters ) in front if you wanna make it on the easier, but the visible jumper wire looks awfull

ballast jumper

What distributor? Asking because the rotor needs to be phased with the cap terminals.

easiest way to change RP is to drill another hole for the roll pin (I forget what size drill bit) in aways from the ID then rattail file it back out to the center ID with a mini round rattail file. You are duplicating the ones Andy premiered way back & Eberg was selling em. measure twice & if you are off there is room for more tries (there's had 5 or 6 holes). this takes care of the circumferential arc gap & reduce the radial gap with an Echlin MO3000 rotor ($8.xx out the door) that is .060" longer or drill out the rivet on your stock rotor & sub in a strip of brass & shoot for .015" clearance (with tight bushings). EDIT & dremel clean/sharp edges on the cap terminals/rotor tip as it takes less required voltage to jump from sharp to sharp surfaces than rounded one (helps at WOT when available voltage from the minimal rise time is the least).

wondering about the relation between original question and the reluctor notes LOL

Nacho, we're having a bad day are we! It'll pass.

LOL, well since couple of years ago I haven't had a good day really, but I'm somehow fine at this moment... I was just wondering LOL

Thanks, I needed to know if I should bypass both sides or not, looks like I need to!



https://www.ebay.com/itm/TSP-Mopar-Pro-Series-Pro-Billet-Distributor-JM7613BK/232278200898?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

and an adjustable MSD rotor1

If you need just one source for the ignition system, no you don't need to bypass both, just the one will feed the system which is in any case the same that originally sourced the coil.

the other one is the one would run to the ECU ( green traced red ), which I think you won't use anymore. Or do you ?

If you are keeping stock ignition system you need to keep untouched the ballast AND add an external jumper with a diode.

Diagram made by John Kunkel I think ? on a thread we talk about quite ago, about same deal. Stock ignition still will need to keep ballast. EFI System has noting to do straight with ignition but this will be the way to be able to feed it 12 volts with ballast in place on both ign stages ( run and start )

Diagram is made based on single ballast... dual ballast won't touch the secondary resistor, Jumper just applies to primary resistor

Thanks Nacho.

We have an MSD coil and the FiTech will handle spark control. So I plan on providing straight 12v to the coil.

This would be the wiring to full fill 12 volts to EFI on both ign stages without affect the ballast function for stock ignition system on 4 prongs ballast

Oh Ok! well I don't know completelly the EFI system and the ignition system related.

If so, then stock ECU won't be anymore, so you don't need to bypass the secondary resistor UNLESS you want to get an alternative 12 volts splice coming from it on green traced red wire.

& I coulda been a little bit nicer in my reply.

Thanks.

Can you enlighten me on why a diode is needed here? I understand the function of the diode, but I am trying to figure out where the voltage would be going, if it wasn't there. Would I be trying to power accessories while cranking [radio, fan, etc.].

Nice drawing Nacho. I think the stock ballast with diode should work with either ignition system?

When they said stock appearance, I was thinking the OP was going to use the stock Mopar distributor? It can be made to work with re-phasing the reluctor.
The FiTech instructions and Q&A forum show that no ballast resistor is required when the EFI unit is controlling the ignition coil.
If you keep the stock 5-pin Mopar ECU for looks you don't want a wire shorting / bypassing the resistor going to the ECU, either leave the resistor, or since not using the Mopar ECU anyhow, remove the resistor (open circuit) going to the ECU.
On the other side of the dual ballast resistor, you can add a wire to short/bypass the coils ballast resistor. This will also supply power in both crank and run key positions that the FiTech white wire would connect to. With the dual ballast modified that way, the diode is not needed.

ok, I have to be honest... all what I know about the EFI system is a fuel provision to replace the carburetor. Didn't ( or don't ) really know about it controls the ignition system or coil. However we got a discussion about that quite ago around here and I assumed by the posts there it still needed an ignition system, and the poster on that thread wanted to keep the Orange box. That's the reason why the first diagram made by John Kunkel came up ( updated by me now on 4 prongs setup, colored ), talking between us about how to wire it propperly. Relays, diodes ideas floated up.

Goodys... The reason for the diode there is to allow the full 12 volts coming from ign2 into ign1 circuit while cranking ( START ) to feed the RUN circuit with full voltage in both stages ( to feed stuff like EFI or any other acc which requires 12 volts in both stages ) but NOT feed the ing2 coming from ign1 into RUN, because that will make to feed the coil with full 12 volts allways, making no sense to keep the ballast in place or modified.

Lets see... while you keep the ign in RUN the blue circuit is feeded from ign switch with 12 volts, and the brown circuit is feeded with the ballast source ( 4.5 to 9 volts ).

However while you are cranking ( ign 2 ) the brown circuit is now the one which gets full 12 volts FROM ign switch to bypass the ballast and feed the coil at full voltage for hotter spark while cranking, and the blue circuit ( ign 1 ) is the one what gets back the ballast source ( 4.5 to 9 volts ), not anymore from ign switch. That's the reason you see the brake warning light on cluster ( and oil warning light if equipped ) dimming while cranking since THESE lights are sourced by the RUN circuit ( blue, ign 1 ) into the cab. That ballast power is the one that also sources the stock ECU while cranking ( not the aux resistor, but the main source spliced into the blue circuit ), but is still quite enough to make it work.

clear ?