MSD Ignition Question

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stimpy29

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We're in the final stages of getting my motor fired up and we came across a couple of questions with respect to the MSD ignition setup that we have installed. After reading a few posts here, I think I understand things a little better, but I wanted to post this question just to confirm. My previous motor setup had one of the Chrysler chrome box ignition boxes and for some reason we were under the assumption that it was still required. After reading the documentation from MSD and giving them a call, they say that the box is not required and not compatible. If we want to use an ignition box, then we need to use one of their MSD units. So based on the attached diagram, (the first without a MSD box), in order to follow this setup, we would bypass the ballast resistor and feed 12V directly to the coil. The picture was confusing to us because the ballast resistor is still in the diagram.

Assuming that we are correct, what would be the advantage or disadvantage to not using the MSD box (second diagram)?

Thanks as always for your help.

coil1.JPG


coil2.JPG
 
msd ignition boxes replace the mopar ignition box...

which msd box are you going to use?

the ballast resistor is not used with the msd either...

wiring a msd 6 is pretty straight forward...
 
stimpy29 said:
We're in the final stages of getting my motor fired up and we came across a couple of questions with respect to the MSD ignition setup that we have installed. After reading a few posts here, I think I understand things a little better, but I wanted to post this question just to confirm. My previous motor setup had one of the Chrysler chrome box ignition boxes and for some reason we were under the assumption that it was still required. After reading the documentation from MSD and giving them a call, they say that the box is not required and not compatible. If we want to use an ignition box, then we need to use one of their MSD units. So based on the attached diagram, (the first without a MSD box), in order to follow this setup, we would bypass the ballast resistor and feed 12V directly to the coil. The picture was confusing to us because the ballast resistor is still in the diagram.

Assuming that we are correct, what would be the advantage or disadvantage to not using the MSD box (second diagram)?

Thanks as always for your help.
Click to expand...

The coil with using the MSD does get + feed from the ignition switch still. The MSD is used only to trigger it is all. Positive to ingnition switch which goes to the msd which triggers the coil + ......
 
Without using the MSD you will not have a Rev Limiter or any other type of timing controls that come with the unit. Depending on which one you use like a 2 stage limiter for Nitrous or line lock for the burn out box, launch etc........
 
70aarcuda said:
msd ignition boxes replace the mopar ignition box...

which msd box are you going to use?
Click to expand...
Thanks for the reply. Based on the first diagram, do I need a MSD box? This is where my confusion stems from.

Obviously the mopar ignition box will not be used either.
 
Mad Dart said:
Without using the MSD you will not have a Rev Limiter or any other type of timing controls that come with the unit. Depending on which one you use like a 2 stage limiter for Nitrous or line lock for the burn out box, launch etc........
Click to expand...
Okay, this is just a cruising car, no racing or anything like that. I'm not opposed to using a MSD box, I just wanted to know if there is a disadvantage to not using one, or would the masses say, "hey, you should use one because of this, this and that".
 
the first diagram shows a ready to run distributor, which will have all the electronics built into it....if that is what you have then ...NO you do not need a separate igintion box...

a ready to run distributor will have a igintion module builit into it...it will only need to connected to a coil....


diagram 2 shows a regular electronic iginition distributor....it has no build in control module...you will need to use either a mopar ecu or msd ignition box...

does that help?

and what do you have or are trying to use??????
 
70aarcuda said:
does that help?
Click to expand...
Immensely, thank you.

Right now, I have a mopar ignition box and the msd ignition setup (coil + distributer) without the msd box. To be honest, I don't know if it is a "ready to run", I'll have to double-check. Based on the documentation, I misunderstood what the "ready to run" meant. So if the unit is a ready to run, then I'll forgo the ignition boxes and go with straight setup.
 
What distributor do you have?

Your diagrams show a three wire distributor which is MSD's "ready to run dist"

You Said "Okay, this is just a cruising car, no racing or anything like that." If this is just a street car then I wouldn't recommend that distributor, I would just use a two wire MSD distributor or a good Mopar electronic distributor with an MSD box. The "ready to run" distributor is a good distributor but was designed for street rods and and cars with no room for electronics, that is why they don't need the box. Not to mention they are twice the money of a standard MSD distributor.
 
Sorry if the above questions were already answered, I sometimes type slow.
 
Blownfish said:
What distributor do you have?

Your diagrams show a three wire distributor which is MSD's "ready to run dist"

You Said "Okay, this is just a cruising car, no racing or anything like that." If this is just a street car then I wouldn't recommend that distributor, I would just use a two wire MSD distributor or a good Mopar electronic distributor with an MSD box. The "ready to run" distributor is a good distributor but was designed for street rods and and cars with no room for electronics, that is why they don't need the box. Not to mention they are twice the money of a standard MSD distributor.
Click to expand...
Thanks for your reply and advice. Essentially the motor I have already has this ready to run distributer. So outside of expense, do you see any performance or reliability issue that I should consider with this particular unit?
 
stimpy29 said:
Thanks for your reply and advice. Essentially the motor I have already has this ready to run distributer. So outside of expense, do you see any performance or reliability issue that I should consider with this particular unit?
Click to expand...

I've been told they are good distributors. I am curious though if the shaft alignment if off on them like it is on the standard SB distributors. When I installed mine I had to line the slot in the distributor gear up between the #2 and #4 cylinder to get the rotor to point in the correct direction.
 
stimpy29 said:
Okay, this is just a cruising car, no racing or anything like that. I'm not opposed to using a MSD box, I just wanted to know if there is a disadvantage to not using one, or would the masses say, "hey, you should use one because of this, this and that".
Click to expand...
correct me if i'm wrong, but i think ignition boxes give you multiple sparks, completely burning the fuel, resulting in slightly better mileage?
 
I wouldn't bother with an external box with that. Not in your application. I'd only upgrade to adding the box if you are having problems with it misfiring. And unless you're running a lot more gear or compression than makes sense for a cruiser, I doubt you're going to run up against the Ready to Run distributor's limits.

The regular MSD box only gives multiple sparks because its sparks are a lot shorter. They're hotter, they're better at firing fouled plugs, but the individual sparks don't give as long a burn, and that seems to cause trouble at low RPM. So they added multiple sparks, pretty much to tame a high RPM racing ignition and make it work at low speeds too. Though I'd imagine it might "re-strike" misfires as well and have a slight advantage. But probably not enough to pay for itself in gas mileage.
 
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