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I recently was getting hard starts after the engine was warm on my 68 F100 390. I thought I had a bad coil. I decided to grab a MSD Blaster 2 and hooked it up. The previous owner left me a wiring mess. Lucky for me, he couldn't read. Otherwise, he would have seen "DO NOT CUT OR SPLICE" written all over the pink resistor wire. I noticed it was getting HOT and not warm under load. I pulled the pink wire out and it was thin and mushy in one spot so I traced it around. I found that it had been cut and spliced near the ignition.
I tried my best to repair it and remove the spliced wire. But, it fried when I tried to put power to it. It burnt right off of the clip. So I need a little help with the repair. I have the MSD and a 0.8 ohms ballast resistor. On a hunch, I popped the distributor and it looks like there is a Petronix igniter in there.
I no longer have a pink wire. But am I right that I can just run 12 volts to the MSD coil, and then run the positive from the Petronix to the positive to the coil (meaning that the igniter would get 12 volts too)? Or, should I run 12 volts from the ignition, to the ballast resistor, then to the coil and Petronix?
What I'm thinking is that since my pink wire conveniently lit on fire right at the ignition switch, I could just run a 12 volt wire from that port on the ignition switch plug and run that right to the MSD coil. I don't think I need a ballast resistor, but I ran a jumper wire to run the engine and I will get 9 volts running at the MSD coil with the ballast resistor hooked up versus 12 volts when starting and running without a ballast.
The pink wire runs from the ignition switch to a clip that and joins a wire to the starting solenoid (gray wire I believe). I think the gray wire is there so that when the starting solenoid is open it sends 12 volts to the ignition wire, and when the starter circuit closes the ignition wire is then only powered by the 6 volt pink wire. Anyway, will it matter if I run a 12 volt hot from the ignition switch straight into the clip with the gray wire? Or, can I bypass the gray solenoid wire altogether and not have the gray wire connected to anything?
Before I forget, it looks like the main power wire to the switch (Yellow) is compromised as well. I see discoloring looks like from heat there at the main connector. It also looks like there are only a couple of strands left. This wire needs to be fully engaged with all of it's conductors, because that's the main power IN to the switch that then goes out and powers everything else.
And yes, you can run your own wire and give the Ignitor's Red wire a full 12v to keep it happy.
IF it turns out you can run the coil on 12v too, then yes to hooking the Red wire to the coil positive and feed both components from the same new wire from the switch.
But that's a big IF with a coil of only .8 ohms resistance. What is the actual part number of the MSD coil?
And it appears to be a Pertronix Ignitor 1 from here. Is that correct? If so you may still need a resistor for the coil only. You still want 12v at the distributor, but might be limited to the lower voltage at the coil due to the Ignitor 1 specs.
If it's not compatible and you'd just rather not mess with a resistor anymore, you could take that coil back if it's not used, and get one that's meant for 12v with the Ignitor.
Before I forget, it looks like the main power wire to the switch (Yellow) is compromised as well. I see discoloring looks like from heat there at the main connector. It also looks like there are only a couple of strands left. This wire needs to be fully engaged with all of it's conductors, because that's the main power IN to the switch that then goes out and powers everything else.
And yes, you can run your own wire and give the Ignitor's Red wire a full 12v to keep it happy.
IF it turns out you can run the coil on 12v too, then yes to hooking the Red wire to the coil positive and feed both components from the same new wire from the switch.
But that's a big IF with a coil of only .8 ohms resistance. What is the actual part number of the MSD coil?
And it appears to be a Pertronix Ignitor 1 from here. Is that correct? If so you may still need a resistor for the coil only. You still want 12v at the distributor, but might be limited to the lower voltage at the coil due to the Ignitor 1 specs.
If it's not compatible and you'd just rather not mess with a resistor anymore, you could take that coil back if it's not used, and get one that's meant for 12v with the Ignitor.
Always good to check.
Paul
Thanks for the awesome answer, lot's of knowledge here. The coil is an MSD Blaster 2 Part No. 8202. After looking around, it seems up in the air whether it's okay to run 12v to the MSD coil. What I do know is that the MSD coil is 0.7 ohms. Perhaps I should run the MSD at 0.7 ohms and the ballast resistor at 0.8 to bring the ohms up to 1.5. That way there isn't too much resistance through the ignition wire to the ignition switch.
What is a good keyed-hot wire? I can't really tell if I have a Pertronix I or not either. If I run a keyed-hot right to the Pertronix, what is a good circuit to run a keyed hot from? I'm assuming that I wouldn't want to share the ignition hot between the ballast resistor/coil and the Pertronix.
The coil is an MSD Blaster 2 Part No. 8202. After looking around, it seems up in the air whether it's okay to run 12v to the MSD coil.
I'll check too, just in case I can find a definitive answer.
As if such a thing ever exists when it comes to our older rigs!
Originally Posted by Jim Lovell
What is a good keyed-hot wire?
Well, since you're messing about with the switch connector anyway, you could add an additional wire to the same connection point at the switch as the old resistor wire. Or, assuming by "resistor" you mean you will be replacing the old melted wire with a new standard wire, and mounting a ballast resistor on the firewall, you can now use the same wire for the coil as you do for for the distributor. Just tap into the wire BEFORE the resistor, rather than after.
If you run a wire from where the ignition wire from the key runs to the resistor, that is still 12v right there. Only at the other end is it lower.
Originally Posted by Jim Lovell
If I run a keyed-hot right to the Pertronix, what is a good circuit to run a keyed hot from? I'm assuming that I wouldn't want to share the ignition hot between the ballast resistor/coil and the Pertronix.
See above. It's ok to share the same post on the ignition switch at this level. You don't want to do that for heavier load items, but neither the coil nor the distributor use more power than the ignition switch can handle. And if you use a 14ga wire at the switch, it should be more than heavy enough to carry all the current needed for both items. With a resistor or not...
Originally, at least part of that burned Pink wire was Red w/green stripe. That's the standard wire color for the ignition coil on our older rigs.
There is a matching (so to speak) Green w/red wire that powers up the voltage regulator for the alternator. It could be used in a pinch too, but being so far away from the ignition parts it would be more messy and use a longer wire. Trying to take advantage of the same part of the switch as the old Pink (or Red w/green) wire would be best.
Looks to me like you can use it without a resistor. I would not want to stake YOUR money on that, but if it was mine I would run it on 12v.
They only specify a resistor if using it with points style ignitions. Nothing about electronic ignitions, except for mentioning the Mallory Unilite which had a rash of failures at one point. They say to use a resistor with them too.
But nothing about others except to say that "most electronic ignitions do not require the use of a resistor" right in their instructions.
The coil might not care, but that looks a lot like a Pertronix Ignitor 1 module. Assuming this is the case, you'll smoke that module. A 0.7 ohm primary winding coil would need an external resistor to drop the current to manageable levels. The voltage at the Ignitor (or points for that matter) doesn't matter too much, up to about 16 volts is tolerable, but amps = Heat, that's what counts and why dropping resistors are used.
Ignitor 1 wants to see a minimum of 1.5 ohms in the primary circuit, to limit current to under 8 amps. I use 14 volts for this calculation and a coil duty cycle of 67% on a V8, meaning the Ignitor module would pass roughly 13.5 amps with a 0.7 ohm coil. Not for very long though.
The MSD coil has to have a resistor inline to drop voltage.
And must be mounted so that the high voltage cable it straight up if oil filled if not the coil will over heat an fail.
The MSD coil is the closest match to the later ford dur- spark ll coils an after my MSD coil failed a few weeks after installing it,I was not going to put out another $40 bucks.
I bought the dur-spark ll coil running the dizzy with the complete dur-spark ll ignition box system an must use the inline resistor that comes with the MSD coil.
Orich
That's good to know guys. Not sure how you arrived at that info, but would like to hear the technical details.
All I was aware of regarding the Ignitor I was that they like the full 12v to the Ignitor's Red wire. Nothing about current needs.
And Orich, is that voltage drop needed due to the Ignitor? Because MSD themselves say in their instructions that there is no reason to add a resistor if there was not one needed for the distributor.
Unless I'm interpreting what they're saying incorrectly. Which is very possible!
That's why I like to know though, so any info you guys can share would be very much appreciated for sure.
Don't want to be the guy that fried a member's coil from lack of information.
That's good to know guys. Not sure how you arrived at that info, but would like to hear the technical details. All I was aware of regarding the Ignitor I was that they like the full 12v to the Ignitor's Red wire. Nothing about current needs.
OK walk down memory lane. Point distributors back in the day were limited to around 3 or 4 amperes through the primary ignition circuit or the tungsten contacts would get burned. But the engineers wanted a hotter spark for more reliable starting, especially in cold weather so they used a resistor divider network, splitting the total resistance in the primary roughly in half, introducing a separate ballast resistor in the primary ignition circuit to reduce the current flow when engine is running. I think this was actually a result of the switch from 6 to 12 volts. The coil, points, and condenser were basically "6 volt" more or less and remained so. Ballast resistor is bypassed at the solenoid during engine start so full battery voltage is applied temporarily for a hotter spark. When the key is released to RUN the ballast is in circuit. A Ford coil had about 1.5 ohms, the ballast wire was around the same. So roughly, 3 ohms total.
The ignition coil has two separate windings, the primary and secondary, the primary windings are heavy gauge wire with a few hundred turns maybe and connected to ground through the points. The coils don't actually have a resistor inside them but their resistance depends on the total number of windings they have. With no arcing contacts, the electronic modules, or switches really, can take more current than contact points. Ignition coil designs can also take advantage of this and have a hotter output by varying the turns ratio between primary and secondary windings. More voltage more current more coil = hotter spark.
The reason everybody gets confused on the Pertronix deal is they sell a few different Ignitors, and they also sell a few different coils, for different applications. Add to that some people want to use the Pertronix hot Flamethrower 40k coil with their older style stock point distributor, some people want to use their new Ignitor module with their old point coil. Some people want to use both. Some people though, try to use the very low ohm coils with the Ignitor 1 and burn it up. And every other combination you can think of. The instructions vary on whether the external ballast can be removed or bypassed depending on what particular part or combination of parts is being installed.
Pertronix has a pretty good website that explains the requirements for their different modules as well as a tech line. It is best to run the Ignitor 1 module without any external ballast but this assumes the ignition coil has a primary winding resistance of at least 1.5 ohms. The Ignitor 1 module is pretty tolerant on wide voltage swings but excessive current flow will burn them up.
Pertronix cautions not to exceed 8 amps through the ignition primary for the Ignitor 1 module. I've ran an Ignitor 1 for twenty years now with straight battery voltage and a generator charging system and had no problems. I just ran a heavy gauge wire direct from the ignition switch to the + side of the coil, bypassing the "pink wire". I have an extra distributor setup with points & condenser installed and gapped &c, ready to go in case the Ignitor ever fails out on the road.
Since I don't want to mess under the dash again or ballast resistors in a situation like that I picked up a Bosch blue coil to install with it, a 3 ohm coil and works safely with a point distributor under that situation, though losing the extra jolt normally provided for starting. But in theory at least I can swap just the coil & distributor out and be back on the road pretty quick. I could also just use the 3 ohm coil with the Ignitor module and be done with it, but a 1.5 ohm coil should provide a hotter spark, and a spare is a spare in any case.
The current flow through the primary is where the concern is no matter what you run. Voltage doesn't have that much to do with it. Measure the total ohms resistance of the primary circuit. This just means the coil, between + and - terminals. Pertronix has 3.0, 1.5, 0.7 ohm and even a 0.2 ohm coil iirc, but using these low ohm coils with anything other than their Ignitor 2 or Ignitor 3 is going to roast something. You could use any coil, points, Ignitor module etc, whatever you want and in any combination or brand so long as current limits aren't exceeded. 3 amps or so for points, 8 amps for Ignitor 1, etc.
I'll check too, just in case I can find a definitive answer.
As if such a thing ever exists when it comes to our older rigs!
Well, since you're messing about with the switch connector anyway, you could add an additional wire to the same connection point at the switch as the old resistor wire. Or, assuming by "resistor" you mean you will be replacing the old melted wire with a new standard wire, and mounting a ballast resistor on the firewall, you can now use the same wire for the coil as you do for for the distributor. Just tap into the wire BEFORE the resistor, rather than after.
If you run a wire from where the ignition wire from the key runs to the resistor, that is still 12v right there. Only at the other end is it lower.
See above. It's ok to share the same post on the ignition switch at this level. You don't want to do that for heavier load items, but neither the coil nor the distributor use more power than the ignition switch can handle. And if you use a 14ga wire at the switch, it should be more than heavy enough to carry all the current needed for both items. With a resistor or not...
Originally, at least part of that burned Pink wire was Red w/green stripe. That's the standard wire color for the ignition coil on our older rigs.
There is a matching (so to speak) Green w/red wire that powers up the voltage regulator for the alternator. It could be used in a pinch too, but being so far away from the ignition parts it would be more messy and use a longer wire. Trying to take advantage of the same part of the switch as the old Pink (or Red w/green) wire would be best.
Paul
The wire that the PO spliced into the pink wire was red with a green stripe. I'm still trying to figure out what it goes to, I haven't traced it back. My 68 wiring diagram doesn't help either. Do you think it my red w/green stripe used to be attached to the pink wire further back? See pic below.
First off Jim Lovell, definitely use the resistor if you're going to keep that coil.
In looking at my own website I was looking at the Flame Thrower I, II and III coils with varying ohm ratings, and they seem to always come back to the 1.5 ohm value with the Ignitor I you seem to have in your distributor.
It varies by number of cylinders sometimes (they don't say, but I'm guessing it's the change in dwell angle values that creates this distinction) but for a V8 and your setup, you need to go by the Ignitor needs and not what MSD says about their coil.
If I was a conspiracy theorist type, I might think that MSD was leaving out any particulars that would help an Ignitor live long and prosper, in the hopes that after frying a couple of modules, you as the consumer would get fed up and buy one of MSD's distributors.
If I was prone to thinking those thoughts, that is...
Originally Posted by Tedster9
...I think this was actually a result of the switch from 6 to 12 volts. The coil, points, and condenser were basically "6 volt" more or less and remained so. Ballast resistor is bypassed at the solenoid during engine start so full battery voltage is applied temporarily for a hotter spark. When the key is released to RUN the ballast is in circuit.
Well, that's what I thought too, until I was put back on my heels recently, about just that aspect. Several members (either here or on classic, I don't remember) said that it had nothing to do with the transition from 6 to 12 volts, and the resistor was there only to create a hotter spark, or something like that.
Didn't make sens to be at the time (and still doesn't by the way) but they know way more than I do about electrical theory. And even one of the descriptions in the Ford book for '79 said something quite similar.
Unfortunately, none of them (members nor Ford) really explained it in any clear language. I could hear the words, but not understand the concepts the words were trying to put forth. Still don't...
Maybe if I can find the discussions, you can make sense out of them. If you do, then maybe you can clear it up for me too!
Originally Posted by Tedster9
The ignition coil has two separate windings, the primary and secondary, the primary windings are heavy gauge wire with a few hundred turns maybe and connected to ground through the points. The coils don't actually have a resistor inside them but their resistance depends on the total number of windings they have.
Total number of windings, and presumably the size of the wire?
Guessing this primary-to-secondary winding is the "100:1" ratio that they talk about in the particular case of the MSD #8202 in question?
Originally Posted by Tedster9
The reason everybody gets confused on the Pertronix deal is they sell a few different Ignitors, and they also sell a few different coils, for different applications. Add to that some people want to use the Pertronix hot Flamethrower 40k coil with their older style stock point distributor, some people want to use their new Ignitor module with their old point coil. Some people want to use both. Some people though, try to use the very low ohm coils with the Ignitor 1 and burn it up. And every other combination you can think of. The instructions vary on whether the external ballast can be removed or bypassed depending on what particular part or combination of parts is being installed.
Might come down to the II and III modules are utilizing what they call variable dwell? They even list certain coils as being compatible with whichever Ignitor, but only some are compatible with both 8-cylinder and 6-cylinder engines at the same time.
With one you might have to use a resistor, and the other you don't.
I went through their information and talked to their tech line extensively a few years ago when I added the descriptions on our web page (https://www.wildhorses4x4.com/catego...anceignition/a) for each of the Pertronix coils, to make sure it was easier for a customer to make a decision, or to go back later and view the info to make sure that the coil was compatible with their use.
I never got down to the nitty gritty of amperage or dwell times though.
Originally Posted by Tedster9
The Ignitor 1 module is pretty tolerant on wide voltage swings but excessive current flow will burn them up.
That's only been my experience sometimes. We've run them on Broncos for years and sometimes they run flawlessly even when fed through the original resistor wire, and sometimes they spit and cough and put out a very erratic spark.
Poor voltage (whether through an actual resistor, or just an old tired wire or connection) has led many an old car owner on a wild goose chase. So I always recommend using the best circuit you can to make sure you have full system voltage to your Ignitor.
Originally Posted by Tedster9
Pertronix cautions not to exceed 8 amps through the ignition primary for the Ignitor 1 module. I've ran an Ignitor 1 for twenty years now with straight battery voltage and a generator charging system and had no problems. I just ran a heavy gauge wire direct from the ignition switch to the + side of the coil, bypassing the "pink wire". I have an extra distributor setup with points & condenser installed and gapped &c, ready to go in case the Ignitor ever fails out on the road.
Done the same thing many times myself. I just never hunted down how to factor and figure out how much amperage a particular ignition system would run through the module.
Again, would love to have that equation ready to hand when figuring out the proper ignition components for someone.
What actually determines the amperage drawn through an ignition system like these? How do you figure it out without their data listed? Do you use a generalization and take their claimed voltage output of, for example, "45,000 volts" and do some math? Or do you have to ask them?
Or can it be figured out with other information based on your own particular components?
Just wondering how you figure out if your system is going to allow your trigger mechanism to see 3, 5, 8, or 10 amps.
09-17-2018, 10:56 PM
and not warm under load. I pulled the pink wire out and it was thin and mushy in one spot so I traced it around. I found that it had been cut and spliced near the ignition. 
