Hey guys, in my latest endeavors, there are so many things going on with the truck. Just a quick question. My 300 takes a duraspark 2 system. I have the distributor and box, I just need the harness, which i'm working on. Anybody by chance know how i'd convert from a 1968 points system from my truck, to the duraspark 2? Specifically, where the harness adapts or hooks up to? Thanks

 

Hot-in-RUN power goes to the coil positive (BATT) terminal through a 1.3-ohm resistor wire; this will already be in place on your points setup. Hot-in-START power also must run to the positive terminal of the coil from the 'I' post of a 4-terminal starter solenoid. Your points setup may already have a hot-in-START signal coming from the ignition switch, but this will need to go to the new ignition module.

Hot-in-RUN power goes to the RED wire of the ignition module. Hot-in-START power from the ignition switch goes to the WHITE wire of the ignition module. The rest of the connections (coil negative terminal, distributor, and module 4-connector pigtail) are self-contained in the Duraspark harness.

Here is a wiring diagram for reference:

 

Sounds simple..is it just pretty much plug n play?

 

While not overly complicated, it's not plug and play.

 

Ok..so ill plug the box straight into where the existing one is? Then the box..then the plug from the distributor to the box. The resistor goes between the box and ignition.. where do I ground the coil? am I right so far??

 

Your multiple threads back and forth on this are getting confusing.

I can't follow your post. If you are upgrading a points setup to Duraspark, there shouldn't be an existing "box" (assuming you are referring to the ignition module). With regard to your comment about the ballast resistor, I am not sure what you mean by "ignition." That's a very generic term in this case. This entire setup is "ignition." I am speaking in terms of exactly which wires go where.

The coil does not get grounded. This is the job of the ignition module. The ignition module grounds and then un-grounds the coil to create a voltage on the primary winding, which is then reflected across the secondary wiring to form the spark. This happens over and over as the engine runs to fire each cylinder.

Instead of you trying to repeat what I've shown with vague generalities, and then have me guess if you're right or wrong, please just follow the diagram and the instructions I gave in my first post. You need to wire it exactly as shown - nothing more, nothing less. If something about the diagram is not clear, then please ask me to clarify. However, the diagram leaves little to the imagination; it's very explicit.

 

I'm sorry about the flip flop. I came back to look at the wiring diagram. As I've already stated..I do not know how to read wiring diagrams..even as "straightforward" as they may be. I'm converting from points yes..I have the box and the whole duraspark components ordered in. I was asking if the coil was grounded because the coil I have for the truck has two terminals..a positive and negative. I realize all of this is " ignition" ..I meant ignition switch. I can't just LOOK at something and know how it is..sometimes some instruction DOES help. If you are getting frustrated..you don't have to reply. Respectfully saying and no hard feelings

 

I'm not getting frustrated, and I'm happy to help. However, if you re-read your post you will find that it was quite confusing.

I understand that a wiring diagram by itself may be difficult to follow, which is why I preceded it with a written explanation of how things connect. I certainly do not mind adding clarification if it is needed. Can you please describe which item is causing confusion?

 

I truly do not mean any disrespect..I truly do not know how to read a wiring diagram. I do apologize for all the flip flop. The research that I've looked at is that alot of guys put the ballast resistor between the the positive coil wire and the control box. Does the control box connect to the starter relay? If i'm not mistaken it does..I believe my frustration comes from the PO's wiring label job and the jumble of a mess I've had to untangle. So, once again..i do apologize.
As to answer your question...if I may describe this in the most unconfusing way haha...I'm going to try to describe this without a diagram..
The wiring that comes off the box with the pigtails that go to the distributor..has two other wires on it. One goes to nowhere and the other to a plastic horseshoe type thing..the po labeled the 2 wires that come off of it as "coil pos" and "tach". then theres a wire with a really small rectangle head at the end....my frustration begins here. What wire do i connect to the starter relay? and what wires to I connect to the two terminals on the coil? I know the small rectangle end goes to the existing wiriing harness...again..i hope you can follow. this is the best I can describe while looking at it..

 

Again, no worries.

No, this is incorrect. The ballast resistor's job is to drop the voltage to the coil when the key is in RUN. Therefore the ballast resistor goes in between the positive terminal of the coil (BATT) and the RUN terminal of the ignition switch. The ballast resistor is the zig-zag item shown in the diagram. Looking at the diagram, you will see that each end is connected as I have just described. The wiring diagram is simply a tool to demonstrate the idea using pictures.

The ballast resistor is actually a long length of wire bundled in the dash harness. It is already part of your wiring harness on a points setup, so you do not have to do anything to add this. In other words, the positive terminal of the coil remains unchanged (the connection from your truck that goes to the positive terminal will still go to the positive terminal whether you have points or Duraspark).

Here is the starter solenoid's role in the ignition system:

1) You already have a small terminal labeled 'S' on your existing starter solenoid. If your wiring is untouched, then you have a RED with BLUE stripe wire running to it. This is hot-in-START power from the ignition switch. You will need to run this hot-in-START signal to the WHITE wire of the ignition module. The WHITE wire is part of the smaller two-terminal connector.

2) You should also have a second small terminal labeled 'I'. This does not touch the ignition module, but instead goes to the positive terminal of the coil. This is what is labeled as "START BYPASS" in the wiring diagram. Just like the ballast resistor, this is already there for you in your points setup, and you do not need to do anything.

At the end of the day, the only NEW things you need to add are the power to the ignition module. Everything else is already there, or self-contained in the Duraspark harness. The only exception is the negative terminal of the coil. In your points setup, this came as a single wire from the distributor. With the Duraspark setup, this changes to the GREEN wire coming from the ignition module (you will also notice this in the wiring diagram).

 

And if I may ask a question..albeit probably a stupid one..what does the negative terminal go to on the coil?

 

Not a stupid question. Refer to my previous post:

 

Ooookay..gotcha. the green wire I have is the one labeled "tach" for some reason. Ok..that clears that up. Now..about the resistor...since I have one in the wiring already..do I still need the porcelain block? I also found the red and white wires and the 2 prong plug in to the control box. Will I just splice these wires to their respective places on the harness? And since the resistor wire is already in place I won't have to use the porcelain block? Kind of repeating myself..didn't mean to..but it made sense in my head

 

That's fine; it's labelled as such because a tach would connect to the same location. It's the trigger signal from the ignition box.

If your wiring is original and has not been cut up or modified, you do not need the porcelain block because the ballast resistor is already part of the wiring harness. You would only use the porcelain block if you're starting from scratch or someone has cut up your wiring. The porcelain block is just an aftermarket ballast resistor.

That's correct. One of the wires goes to hot-in-START. You can borrow this signal from the 'S' post of your starter solenoid. The other wire is hot-in-RUN. I am not sure of a convenient place for this on a '68, but you want something that is powered up anytime the key is in RUN.

Here's where it gets confusing: for the first production run of Duraspark modules, the RED wire was hot-in-START and the WHITE wire was hot-in-RUN. If the module has the original Duraspark logo with lightning bolts and says something like "TESTED TOUGH," it might be an original-style module.

Some time later these got reversed, such that the RED wire is hot-in-RUN and the WHITE wire is hot-in-START. Because there are almost no original Duraspark modules actually in service, almost any module you find will be the later kind (RED = hot-in-RUN, WHITE = hot-in-START). Any NEW module you buy will be this same way. As such, my diagram reflects this later method. It's just something to keep in mind if you have problems getting things working.

 

Ah..thanks for the clarification. I believe I have a later box because it doesn't have the lightning bolts..so ill splice the red wire to hot in start and find a place for the white wire. What is the plastic horseshoe thing that all this is on?