johncr

Hi guys,
I know MSD hookup questions have been asked and answered many times in the past, and I think I’ve read most/all of them, but since I’m pretty sure that I fried my original MSD box last weekend, I just wanted to get a better comfort level before I try to wire up the new box.

Background:
I have just completed the rewiring of my ’66 coupe. I’ve attached all the wires per the AIM and Doc Rebuild Laminates.
Inplace of the stock coil and distributor, I have a MSD distributor, blaster coil and a MSD 6 A box.

The original MSD parts were installed by a speed shop and worked well w/no problems. When removing the original harness I saw that the thin red wire was spliced into the ignition harness under the dash.
I read here that the thin red wire could be attached at the ballast resistor and since I didn’t want to start cutting into my new harness, I thought that was the best way to go.

The thick red (+) and thick black (-) wires are attached at the battery; the orange and black are attached to the coil at the + and – terminals, respectively; and the purple and black wires are plugged into the distributor. The MSD box is attached behind the driver’s side front wheel well.

Questions:
Ballast Resistor:
A. Wiring:
1) The single pink wire coming out of the firewall grommet is attached at the bottom of the ballast resistor.
2) The pink wire from the engine compartment wiring harness is plugged into the top of the ballast resistor.
3) The thin red wire from the MSD box is attached at the bottom of the ballast resistor.
Is this correct?

Should any other wires be attached to the ballast resistor with my MSD setup?

B. I also saw where the ballast resistor isn’t needed if the distributor doesn’t use points. If the ballast resistor is eliminated, what happens to the thin red wire, and two pink wires that are currently attached?

Coil:
C. The orange and black wires from the MSD box are attached to the + and – terminals, respectively. The two stranded pink wires/one connector are also attached to the + terminal as shown on the AIM.
I read on somewhere that ONLY the orange and black wires from the MSD box should be connected to the coil. Is that right?

D. Is everything else, such as the alternator and voltage regulator hooked up as normal?

Like I said, I’m pretty sure I burned up my original MSD box last weekend with a stupid mistake. I got a new one on order and hopefully I can get back on track this weekend. I’m a total imbecile when it comes to electronics and I don’t want to risk any more mistakes.

Everything else seems to check out OK. All the lights work, none of the fuses have blown (yet), and the engine cranks. I’m just not getting any spark. I checked the coil with a multi-meter and it checks out.

I’m so thankful for all the great information available here. I never would have tried to tackle this project w/o all the great recommendations and information. Thanks for all your great advice!!

Sorry this is so long.

Mossy66

The wire in the engine side that is connected to the top of your ballast resistor would have gone to the distributor. Where does it go now? It shouldn't be needed anymore with the new distributor. If the ballast resistor is no longer needed, then you just use the connection at one end as a splice point to get your +12v when the ignition is on.

Check to make sure what side of the ballast resistor the wire from the ignition switch is attached to. You may have it backwards there. Also, there is a white wire that should be taped off on the MSD box.


Gerry

johncr

Thanks for your reply Gerry.

Check to make sure what side of the ballast resistor the wire from the ignition switch is attached to. You may have it backwards there.

I'm pretty sure that the 2 pink wires on the ballast resistor can only hook up to the resistor since they are too short to reach the distributor. I may have them reversed on the resistor, that was one of the things that I was wondering about. I thought that the pink wire that comes out of the firewall grommet near the windshield wiper motor was the ignition lead but maybe it the one coming off the engine compartment wire harness. Still a little confused. Which side of the ballast resistor should the pink ignition switch wire be attached to, the top or bottom?

If the ballast resistor is no longer needed, then you just use the connection at one end as a splice point to get your +12v when the ignition is on.

So the ballast resistor is being used as a splice point in this situation (MSD distributor)? In other words I could loose the BR and just splice the two pink wires together?


Check to make sure what side of the ballast resistor the wire from the ignition switch is attached to. You may have it backwards there.

Sorry if this is a stupid question but if the BR is a just a splice point now, does it matter if the two pink wires are reversed?

Also, there is a white wire that should be taped off on the MSD box.

The original installer got rid of the white wire. I don't know how. I imagine that it was cut and pushed up into the insulation. All I know is I can't see it now.

How about the red wire from the MSD box. It that attached correctly? Should it be attached to the top or bottom of the ballast resistor?

If I were to eliminate the ballast resistor, where would you recommend I attach the red wire?

Thanks for your help!

John

Mossy66

The red wire from the MSD is for key on 12v. Connect it at the same point on the ballast resistor as the wire from the ignition switch. The wire on the other end of the ballast resistor should be disconnected at both ends. Yours looks like it is still connected at the coil and at the ballast resistor. That's probably why you aren't getting any spark. At least take it off the coil and tape it off. You only want the wires from the MSD box to go to the coil. That is what will switch the coil on and off to generate spark.

The pink wires that you have attached to the coil was for use with the contact points. One would go to the ballast resistor for reduced current through the points while the engine is running. The other one went to the starter, and it would allow full current to the coil while cranking the engine for a hotter spark while starting. You don't need those wires to the coil with the MSD box. Pull them from the coil and tape them off. We don't want them shorting out.


Gerry

40ZR1

Is the ballast resistor needed? I thought the resistor dropped the voltage from 12v to 6v and not needed?

CJ

Mossy66

No, the ballast resistor is not needed for the MSD box. It's purpose was to reduce the current through the points to help them last longer.

It can be removed, but it's just a handy spot to make a connection to 12V key on if you leave it in place.


Gerry

johncr

Thanks again Gerry,

I'll have to check my wiring diagrams when I get home but I can give you a little more info regarding the 4 pink wires that are in play:

the two pink wires that are attached to the coil come together at their ends with a single spade style connector. I didn't connect them. I'm assuming that this is original since the harness is new and it came that way. These two wires come out of the engine compartment wire harness that runs along the back of the engine compartment, just over the windshield wiper motor (sorry, I should have included a photo that shows this).

The pink wire at the bottom of the ballast resistor comes through the grommet at the firewall near the windshield wiper motor (see photo).

The last pink wire that is attached at the top of the ballast resistor comes off the same engine compartment wire harness as the first two only more to the right of center (as seen in the photos).

You don't need those wires to the coil with the MSD box. Pull them from the coil and tape them off. We don't want them shorting out.

I'll try removing the double pink wire off the coil later today and see if I get a spark.

Thanks again.

buns

That is correct. And like Mossy66 said, you don't need any of the other pink wires. They originate at the R terminal on the starter solenoid and only have power when the starter is engaged. I would remove the pink wires from the R terminal and from the coil and ballast and tape them up out of the way.

johncr

Hey Buns,

Thanks for jumping in.


That is correct. And like Mossy66 said, you don't need any of the other pink wires.

Ok, so if I'm getting this correct, I join the thin red wire from the MSD box to the pink wire coming out of the firewall grommet (ignition lead) and all the other pink wires are now useless and can be taped up. Correct???


I'll try removing the double pink wire off the coil later today and see if I get a spark.

FWIW
I removed the double pink wires from the coil and still no spark. I'm 99.99% sure my MSD box didn't survive the weekend. The good news is the new one will be here tomorrow.

buns

Have you checked for power at the pink wire that comes through the firewall? Check it with the ignition switch in the 'run' position, as well as in the 'start' position. Could be as simple as a boogered ignition switch or a bad connection at the connector.

The terminals that enter the backside of the connector have a 'tit' on the back that prevents them from getting pushed out when you push the connector on. Could be that it wasn't locked in place.

johncr

Just checked the pink wire coming out of the firewall grommet. It shows 12 v when the key is in the start and run positions. So I guess once I wire in the new MSD box I'll be back up and running..... I hope.

I'll follow up either way.

Thanks to everyone for all the help!!!

babbah

I'm running a 6A for decades. None of my cars factory wiring is in the mix. It's a very simple set up. 5 wires and the Mag pu cable. And no ballast resistor. Mine is a factory TI car.
That's it.
Go to the MSD site and see the illustration as to how to wire it and TEST it.
It's simple.

65tripleblack

Not only is the ballast not needed, but that is probably the cause of your problem. It should NOT be used with your style coil. Use the ballast as a junction, but don't run current through it.

johncr

Hi everyone,
I just wanted to let you all know that I replaced my MSD box, wired the new one in per the instructions and the recommendations I got here. All is well and my car is up and running again. I decided to eliminate the ballast resistor, as recommended. I already knew that that was an option, but I was thinking that the engine compartment would look a little more original if it was still there. Of course, if you saw my car you would know that the originality horse left the corral a long time ago.

Anyway, I just wanted to thank everyone who help out and responded to my post, as well as everyone else on the forum. I don’t know what state my car would be in if it wasn’t for this forum. It is a remarkable asset.

For the next guy who is replacing his wiring harness and is wondering which wire to attach the thin red wire from his MSD box, and which of the 3 pink wires to use, here's what worked for me. Attachment of all the other MSD box wires is pretty straight forward.