I would vote either a duraspark or installing a transistor(few buck at radio shack+ some bragging rights) if you wanted to keep it simple, even the pertronix would be a good answer.

now for the geek in me to come out, cause im a fan of new tech in old iron, for a little more cash and a little learning, you could get a megajolt and some 4.6 coil packs. and do away with the distributor and have the perfect timing curve.

 

You guys do know this thread is 10 years old, right?

It got bumped to the top because a new user asked a completely unrelated question about the ignition noise suppression capacitor. I answered that guy's question, but the OP is probably long gone.

 

I never look at the date! information is always a good thing!

 

I saw that it was an old thread, and it was bumped by a new user. But, since new reply's were added talking about the pertronix, I had to ask about this setup.
Doing a little research, it turns out I have had prior experience with this setup, best I can tell. The system I used some ~25 years ago was simply labeled as "Ignitor", though it could have had more wording on the label that I just don't recall.

It appears the current Pertronix systems aren't any pricier than what a DS2 dist and good quality "blue" DS2 box would cost, and is a bit more "plug and play". I'm savy enough with the DS2 setup that I could wire it up *without* modifying the factory 74 harness.
I'm not sure which way I'm gonna go just yet, but the breaker point system is just too much upkeep to maintain proper tune.
Pertronix has one advantage. Keep a set of points and condensor in the glovebox, in case of a system malfunction out in the middle of nowhere. It could be the difference in driving home, or walking. Years ago, when my old conversion kit failed, I was glad to have the P&C in the glovebox (habit from running that setup anyways), cause I was *only* 30 miles from the nearest town, and cell phones were still more than 10 years away from being invented........


I've even considered a DS2 dist and GM HEI, but those GM parts are too prone to fail.......



And, I agree, info is good, no matter how old it is.

 

hay,I'm running a 390-30 over in a old v-drive drag boat that I restored, switched in a 76 duraspark distributor & ICM,I was running the same coil (with a external capacitor that I ran on the points distributor,and it seem to run fine for a while,then I was talking to this mechanic and he seem to think that this ignition system doesn't require a capacitor I'm also looking for the wiring color code for the (schematic)for wiring this brain box ( wanting it right)give me some feed back..../ Steve

 

Is this what you want?

 

I know that diagram shows the red wire getting 12V for the run circuit, but in my past experiences adding a DS2 system, the modules tend to burn up with 12V going to the red wire. I usually wire it up with a resistor to drop the voltage to around 9V, like the older breaker point coils use.

As such, I typically use the factory resistor wire to power the red and coil (if present or a ballast resistor when not present), and a 12V in start-only mode for the white (the "I" terminal of the solenoid is a good source for this). The white wire activates the "start retard" circuit in the DS2 module, though some cheap replacements don't bother using this feature.
The other plug is pretty much just match the wire colors to the dist, and the leftover green goes to the - side of the coil, just like a tach pickup lead. The stock points-type coil can be used, or a DS2 coil can be added for a bit hotter spark. A TFI coil is also useable, for the hottest spark of any "stock" replacement coil, though I believe the TFI coil needs 12V to achieve the correct spark voltage.

 

I tried to answer your follow-up question that you asked me on my visitor page, but it says my answer was too long. Here is what I was going to say:

The capacitor does not affect the running voltage. The reason the voltage at the coil is on the order of 7 to 8 volts while the engine runs is because the ignition coil is powered through a ballast resistor in the wiring harness. As such, part of the full 12 volts drops across the ballast, and the rest drops across the coil. This is by design. This is not the case while the engine is being started because the ballast resistor is bypassed, but because the starter is engaged, the overall voltage is reduced. Using this method, the coil voltage stays fairly consistent between start and run modes.

The ignition noise suppression capacitor has nothing to do with the DC voltage level at the coil. It's simply a filter capacitor to shunt high-frequency noise to ground that is generated as the coil switches rapidly. It's used on both points and electronic ignition systems because ignition noise on the radio is independent of the ignition trigger mechanism. Your mechanic friend is mistaken when he says that the principle is different for electronic ignition systems. The principle of the current through the coil primary winding changing very rapidly is the exact same. It's the principle for how the coil is triggered that is different.

 

Another 10 year old thread revived, but what the heck...

I actually like the Accel drop-in unit (I think it's #2020) and identical to a Mallory unit. Cheap, too, as I've found them on Ebay for as little as $35. I have a few and they've been reliable units. Had them in two vehicles and only one failure in like 10 years--even then, I'm not sure how long the PO had it in one of the vehicles. Dropped another one in and was good to go (didn't even need to mess with timing.)

 

So far I've never had a problem, knock on wood. What I'd love to see, is a diagram of the internal components of the module. Must be proprietory info as I've never been able to find it.

 

This is incorrect. Adding a resistor in series with the supply input to the module will make the module's supply voltage travel all over the map as it pulls current that changes with time. If the module pulls very little current, the supply voltage will still be 12 volts as there will be no drop across the inline resistor. As the module pulls current, the voltage at the module will drop. There's no way to claim that it stays at a constant 9 volts - and a conventional handheld meter will not be able to react fast enough to tell you what's really going on.

The reason ignition coils on Fords, and several other makes, are powered through a resistor is because the ignition system is designed to operate on the low voltage that is available from the battery while the starter is engaged, while the key is in START. Once the key returns to RUN and the starter stops, the voltage rises back to 12 volts. The ballast resistor is placed in series with the coil primary winding in RUN mode to drop the coil voltage back down, so that the voltage is fairly constant through the entire process.

As such, the coil primary winding, and the points (or in the case of electronic ignition a power transistor) are rated for the reduced current as a result of the ballast resistor. It's not related to the supply voltage of any sort of ignition module. If you were frying modules at 12 volts, the module was bad. If you've placed a series resistor inline with the supply to the module and it's working, it's not because the resistor solved the problem, it's because the module wasn't bad in the first place.

If you install a Pertronix system on a Ford, the instructions are very specific in stating that the coil must be powered downstream of the ballast as per the factory setup, but the Pertronix module itself must be wired upstream so as to receive a full 12 volts. Many people make the mistake of connecting the Pertronix module to the coil voltage, and blame Pertronix for the failure.

 

Not to be arguementative or anything, but.....

It may be "incorrect", but in one day we had 3 modules fail without the resistor. 2 were Motorcraft, and one was the high dollar Ford Motorsport/MSD unit. All were purchased new from the dealer parts counter just days before.
Adding the ballast resistor seemed to work, as there was never another module failure on this car (Cobra replica). We had found what looked to be a perfect place to mount the module, before the body went on. With the body in place, it was a great location, as long as you didn't need to change the module.....

I don't see how the voltage would "jump all over the place". A resistor has a fixed OHM rating. As such, the voltage should be the same coming out, as long as the input voltage remains the same. Yes, lowering the input voltage will also reduce the output voltage. I just don't see how the AMP draw, or lack of, could cause the resistor to not drop the voltage. Yes, it *can* reduce the voltage bit more under higher AMP draw, as the resistor can heat up and cause an additional resistance to occur. I can't see it ever allowing full input voltage to pass thru to the output side.

I'm not a highly skilled electrical engineer, but that's my basic understanding of how the whole V/O/A figures would react in this situation. If you can show me proof of it acting in another way, I'm ready to see/read/learn. And, if I'm wrong, I'm not afraid to admit it once I know the correct info.


As for the Pertronix part. That *could* explain why the system I had years ago failed. I hooked it to the + and - of the coil. It did last ~3 years on my truck, and the other lasted over 5 years on dad's truck, both hooked up that way. They didn't come with a box, or even any paperwork. Just a + on the red wire ring terminal, and a - on the black one.....

 

Those things are peculiar. In the beginning I believe they actually called for it to be wired that way for the Ignitor I. Ran them for years on VW's, but no reistor wire there. My son's Mustang was wired the same way and working fine till the magnets let loose. Now they clearly state to run full 12v. May have been a design change, I know they fixed the magnet problem by molding them into the reluctor now. Since I started working on Ford only vehicles, I stay with the Duraspark II. Like you, I can almost wire one in my sleep now and more familiar with it than anything else.

 

Yeah, the old clear tape over the magnets thing bit dad once. 2 weeks after my pickup/module quit. Not sure what went wrong the second time....
The first time he had a problem, he limped home on 5 or 6 cyls. I just happened to be there and outside at the time, so I just handed him the magnet wheel from my setup when he asked if I could go get him some points and condensor. I guess he didn't do like I did, and put some in the glovebox, just in case..... Glad I did, since it failed well out of town. Being the early 80's, cell phones were still a few years away. How did we ever survive without them? By being prepared.....

 

The voltage on the key side of the ballast resistor that you're adding is fixed at 12 volts. The ballast resistor is fixed at 1.3 ohm. The current through the ballast into the module changes with time as the module rapidly grounds and open-circuits the power transistor in the ignition module to fire the coil. With a resistor in series between keyed power and the supply input to the module, the voltage at the module is no longer 12 volts; it's now 12 - I*R, where R = 1.3, and I = the time-variant current into the module. As the current into the module changes, so will the voltage at the module. I'm not saying that the resistor you've added does not drop the voltage, I'm saying it does - and the dropped voltage now moves around. Neither of these effects is desired.

This is only true if the current through the resistor is zero, which is not the case here. As current passes through a resistor, voltage drops across it, hence Ohm's Law (V = I*R).

The concept of a ballast resistor works in series with the coil because the primary coil winding has a fixed resistance. This is not the case for an electronic device such as the ignition module. The effective input impedance of the module changes depending on what it's doing.

If your vehicle is continuously frying ignition modules, then you need to monitor the battery voltage with the engine running, as this is often a sign of a defective voltage regulator. Adding a resistor in series with the module is only a band-aid that does not solve the actual problem; any other electronic device such as a stereo or CB radio will be subject to the same fate.