Considering an e-core coil upgrade - have some questions

[Patrick Morris]

It's been years since I've tinkered with my ignition system other than to change plugs. Lately I've been thinking of replacing the 15 year old plug wires and put on a new cap and rotor. I figure it might be time, though everything's working well.

I've also been reading about possible benefits of the tfi type e-core coils and I figure this is the place to ask.

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but before the questions, here's the current stats:

vehicle - '78 Scout II with 345 v8, 4-spd, 4x4, no a/c. Carburated, Holley 7448, manual choke'

ignition - factory prestolite Distributer with pertronix ignitor for inerds. I'm also running an msd 6 (not a 6a, fwiw). The coil is a jacobs electronics (old school type). Wires are bw, 7mm. Plugs are autolites, gapped to .040, or a hair over. Timing is set at 5* btdc.

Other stuff - distributor is a factory type delco 10si. Battery is an optima, 2-3 years old.

The jacobs coil and msd have been in there since about '93. I swapped in the ignitor in '03. Nothing to complain about with any of this stuff. Everything works fine. The truck passes smog with all the above (except the carb).

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so.... Is an e-core worth the swap? I've read that they are much more "efficient" but how does that help us? And if so, would I just hook it up as shown in the diagram attached?

And as far its resistance is concerned, I know with a conventional coil the resistance is supposed to be 1.5 ohm. With these e-cores I'm seeing them spec'd at more like .4 ohm. Is that okay to just hook up and use?

Btw, in case you are wondering, the wires I was planning to buy are the pertronix flame-thrower 7mm "stock look", which can be seen at the bottom of this page: spark plug wires

Regards,
patrick

 

[Robert Kenney]

With the msd and ecore coil or equivalent don't use any primary resistance wire or ballast. Full hit voltage wise

will a specific coil improve the performance? Depends on what you are trying to burn. Stock compression and cam, probably will make no difference but either way a good quality performance coil with the msd box will be more reliable.

 

[Michael Mayben]

A "tfi" coil is simply a design version that went along with successive generations of Ford electronic ignition systems used with their evolving "eec" electronic engine management scenarios. The "thick film" crap is simply a marketing referral to a particular design element coming into vogue for many electronic devices in the mid-80's, and not just for ignition systems. It's nothing special whatsoever though it is a variation of an "e" core coil, one of the first used in domestic oem applications, though they had been in widespread use in the motorcycle, industrial, and marine engine bizz for more than thirty years!

The Ford-type tfi coils get lots of play simply because they are dirt cheap (if they actually work) in any boneyard, not because they are the hot ticket!

The aftermarket ignition/electrical systems components suppliers introduced their own e core coils more than 15 years ago, in various primary resistance factors to properly match the particular ignition system being installed. Those coils also are available in many different primary resistance factors in order to provide the proper match for the ignition system under consideration.

While some consider dr. Jacobs to be very revolutionary in his approach to ignition system design (read his book which is a major puff piece for his stuff), my personal opinion is..."so what"?? His "systems" were nothing more than a digital version of all the same old capacitive discharge "boxes" that the aftermarket folks were doing. While his coils were real blingy, in actual use they had no actual advantage over any other high turn ratio/high potential output coil on the market at the time. And the jacobs track record for both reliability and "customer service" was abysmal. Today they are nothing more than a disappearing "brand" under the prestolite group of brands.

If your jacobs coil is functional, then there is no reason to change to any other coil. The best performance from a cd box (which is what your msd 6 is) is obtained with the use of a mag trigger (the pertronix is a hall effect trigger) along with a properly-matched low primary resistance coil (no less than 0.3ohms for street use). However, since these engines are not capable of revving more than 5,000rpm in stock form, they do not have a need for an ignition system capable of operating at a rotational speed above that. And...the msd box does provide multi-spark capability at the effective rpm that these sv engines are run on a daily basis.

A "low primary resistance" coil (anything less than 1.2 ohms for a v8 engine application) must be used with a add-on cd box of some brand, simply stacking ballast resistors does not work and will destroy a pertronix module in under 15 seconds of operation if use on such a coil without a cd box.

The add-on cd boxes control primary switching/current, the actual coil primary resistance used with those devices is not a "control" factor as it is in a stock-type inductive ignition system. Big difference. Thus, they can take advantage of the high turn ratio/low primary resistance design factor of the true upgrade/performance coils, most especially when used with high rpm/high compression engine apps. That is why the msd 6 box, the p-tron, and appropriate matching coil all add up to vastly improved drivability on any IH I-4 or sv engine app.

Spark plug cables are a periodic maintenance item. Modern "spiral-wound" (helical-wound) cables are basically all identical, one is no "better" than the other, all are silicone jacketed and use a high quality silicone boot, the important point is always use "boot grease" when installing cables or swapping plugs, and use the proper tool for removing difficult plug boots in order to prevent damage. Any street-operated add-on cd box/coil system must use plug cables that have at least 300 or so ohms of resistance per foot. The "no resistance" cables are used only on drag race apps with actual engine run times at full power less than 15 seconds.

 

[Patrick Morris]

Thanks guys. Lots of info, good stuff to know. But I'm not sure if one of my questions was answered. Just for the sake of discussion:

if I do want to switch to a newer type e-core coil (doesn't have to be Ford app; could be msd, crane, pertronix, etc.) is the diagram I provided valid?

The aftermarket ignition/electrical systems components suppliers introduced their own e core coils more than 15 years ago, in various primary resistance factors to properly match the particular ignition system being installed. Those coils also are available in many different primary resistance factors in order to provide the proper match for the ignition system under consideration.

So, what primary resistance should I be looking for (or avoiding!) with these e-cores if installing one in my system, given the info I've provided?

The best performance from a cd box (which is what your msd 6 is) is obtained with the use of a mag trigger (the pertronix is a hall effect trigger) along with a properly-matched low primary resistance coil (no less than 0.3ohms for street use).

I'm not sure if you mean here that a hall effect trigger is not a mag trigger? Sounds like it. (if not, what kinds of distributors use mag triggers?)

A "low primary resistance" coil (anything less than 1.2 ohms for a v8 engine application) must be used with a add-on cd box of some brand, simply stacking ballast resistors does not work and will destroy a pertronix module in under 15 seconds of operation if use on such a coil without a cd box.

Robert mentioned ballast resistors as well. I neglected to mention above that I don't have one of these on my coil. Never have had one with the jacobs. I'm actually not sure what the pr is for the jacobs coil, now that I think of it , but the truck's been running fine in the 8 years I've had the pertronix, so everything must be compatible.

also, the diagram shows no ballast resistor, so I think we don't need to talk about them as being part of the plan.

The add-on cd boxes control primary switching/current, the actual coil primary resistance used with those devices is not a "control" factor as it is in a stock-type inductive ignition system. Big difference. Thus, they can take advantage of the high turn ratio/low primary resistance design factor of the true upgrade/performance coils, most especially when used with high rpm/high compression engine apps. That is why the msd 6 box, the p-tron, and appropriate matching coil all add up to vastly improved drivability on any IH I-4 or sv engine app.

Could you run by me some examples of what would not be "appropriately matching coils"? Or is it obvious from what you've said so far, like... Don't use one with a pr of less than .3 ohms, nor greater than... 1.2? Don't use ballast(s)?

Other than that and id' be okay?

Spark plug cables are a periodic maintenance item. Modern "spiral-wound" (helical-wound) cables are basically all identical, one is no "better" than the other, all are silicone jacketed and use a high quality silicone boot, the important point is always use "boot grease" when installing cables or swapping plugs, and use the proper tool for removing difficult plug boots in order to prevent damage. Any street-operated add-on cd box/coil system must use plug cables that have at least 300 or so ohms of resistance per foot. The "no resistance" cables are used only on drag race apps with actual engine run times at full power less than 15 seconds.

Sounds like you didn't check out the link, but that's okay. This is why I like the idea of pertronix' 7mm "stock look" wires. As the name implies, they look stock, but internally they are the same as the fancier "flame thrower" wires: spiral wound, with a resistance of 500 ohms/foot. And they don't cost much more than a premium 'stock' set from napa or similar.

And speaking of tools, I've never found one that's worked very well, mainly due to the clearance issues at the #5 and #7 plugs (air-injections tubes and brake system being in the way). Has anyone ever tried this type on an IH engine? It looks like it might work. It's sold under the taylor brand at summit.

 

[RobertC]

and speaking of tools, I've never found one that's worked very well, mainly due to the clearance issues at the #5 and #7 plugs (air-injections tubes and brake system being in the way). Has anyone ever tried this type on an IH engine? It looks like it might work. It's sold under the taylor brand at summit.

I started using that tool (or similar) on my IH a couple years ago.

But, I have a t/a and I think I May have a little more room to get to 5 / 7 even with the air.

 

[Patrick Morris]

I started using that tool (or similar) on my IH a couple years ago.

But, I have a t/a and I think I May have a little more room to get to 5 / 7 even with the air.

Hmm. Thanks. Good to know that it can be slipped in there and hook the boot at least. Worse case scenario I could maybe put a bend in it so that it clears the master cylinder if necessary. Or cut down the handle.

 

[Michael Mayben]

thanks guys. Lots of info, good stuff to know. But I'm not sure if one of my questions was answered. Just for the sake of discussion:

if I do want to switch to a newer type e-core coil (doesn't have to be Ford app; could be msd, crane, pertronix, etc.) is the diagram I provided valid?


So, what primary resistance should I be looking for (or avoiding!) with these e-cores if installing one in my system, given the info I've provided?


I'm not sure if you mean here that a hall effect trigger is not a mag trigger? Sounds like it. (if not, what kinds of distributors use mag triggers?)


Robert mentioned ballast resistors as well. I neglected to mention above that I don't have one of these on my coil. Never have had one with the jacobs. I'm actually not sure what the pr is for the jacobs coil, now that I think of it , but the truck's been running fine in the 8 years I've had the pertronix, so everything must be compatible.

also, the diagram shows no ballast resistor, so I think we don't need to talk about them as being part of the plan.


Could you run by me some examples of what would not be "appropriately matching coils"? Or is it obvious from what you've said so far, like... Don't use one with a pr of less than .3 ohms, nor greater than... 1.2? Don't use ballast(s)?

Other than that and id' be okay?



Sounds like you didn't check out the link, but that's okay. This is why I like the idea of pertronix' 7mm "stock look" wires. As the name implies, they look stock, but internally they are the same as the fancier "flame thrower" wires: spiral wound, with a resistance of 500 ohms/foot. And they don't cost much more than a premium 'stock' set from napa or similar.

And speaking of tools, I've never found one that's worked very well, mainly due to the clearance issues at the #5 and #7 plugs (air-injections tubes and brake system being in the way). Has anyone ever tried this type on an IH engine? It looks like it might work. It's sold under the taylor brand at summit.

Have you not spent any time in digesting the information in this thread?:

http://www.forums.IHPartsAmerica.com/ignition-tech/644-ignition-system-performance-upgrades.html

The answers to nearly all your questions are contained therein. Including several optional scenarios. And all support information for these ignition-related components, including mixing and matching, specifications, and complete installation/wiring recommendations is contained in the support area of both the msd and mallory websites.

Any form of ballast resistor or resistor wire is only used in a breaker point inductive ignition system or in conjunction with the true chrysler electronic ignition system introduced in 1969. No ballast system is ever incorporated into the installation of any cd ignition box, no matter what coil is used.

The chrysler system uses a mag trigger inside the distributor, but an external amplifier to fire the coil in a conventional "inductive" manner, just the same methodology used in the delco hei system, only the amplifier is inside the distributor, similar to what is used in a prestolite electronic distributor which is also inductive in operation. The oem prestolite trigger is hall effect, just the same as pertronix and Holley gold box.

The only reason the Ford-type tfi coil wiring scheme is shown is due to it's somewhat unique connection terminations which were designed to be quick and cheep to install on the vehicle production line, those have no performance advantage whatsoever. Replacement aftermarket coils for Ford apps are designed to use the same oem terminations since the average hobbyist is not capable of performing adequate terminations without a slew of replacement connectors, proper termination tools, etc. The marketing smokeblow about that stuff really pushes the "plug and play" aspect for an oem replacment, not for use in cobbled up systems like we deal in.

The only time the mag trigger input circuit is used on any cd box is when a true mag trigger distributor pickup is being used such as found inside a chrysler distributor, a Ford eec/duraspark distributor, or a delco hei-design distributor. All of the msd and accel aftermarket performance distributors use mag trigger internally. Some mallory distributors use a optical trigger system, some use a mag trigger, some use dual points. The pertronix hall effect conversion does trigger an external cd box, it's simply connected just like breaker points.

A hall effect trigger system is a totally different animal in the ignition world as compared to a magnetic trigger. Just as breaker points are a totally different system as compared to the optical trigger used in both crane conversion systems (xr700 and xr3000) and by mallory (unilite).

The pertronix iii is actually a crane-developed item they took over after the crane bankruptcy, it is a "lobe sensor" design hall effect unit and will not trigger any form of add-on cd box.

The spark plug boot remover you posted is the same ones I use in all my shop and travel tool sets, about $3 locally at any auto supply.

I don't need to check any links! I have all the print catalogs (along with the .pdf stuff) and tons of technical data right here on my desk for all common ignition system components...and I know what each manufacturer offers in the way of products, I do this shit for a j.o.b.!! My personal opinion, the pertronix plug cables are nothing any different or "better" than anything else available as an aftermarket replacement part. Even the common house brand stuff from the big box parts houses are spiral-wound cable, hardly anyone still manufactures throwaway carbon/graphite core cable anymore as it's simply not suitable for use with higher energy ignition systems which require much more sophisticated attenuation of rfi so that the vehicle computer systems don't get stupid. An msd box along with a properly matched coil will produce in excessive of 40kv at 125 millijoules, it takes dam good cabling and boots to contain that kind of heat on a continuous basis.

 

[Patrick Morris]

Thanks michael. Yes, I did read through that a bit before I posted. That is, I read some of it, then skimmed a lot. But to be honest I dismissed much of it because frankly, I don't care about other kinds of distributors or cd boxes, what will work for a 4-banger etc. If there are answers to my questions, they're buried amongst other vast discussions seemingly irrelevant to my specific need. Interesting as they are to some, I don't care about optional scenarios; I only care about my setup, and hypothetically, how I might go about swapping in an e-core coil (and is it even worth the trouble).

I did just read through it again and found this ominous statement:

"msd blaster ss 'low resistance' e-core ignition coil. These must be used only with a cd ignition box if tied into a pertronix trigger. Otherwise, the pertronix will fry in about 30 seconds."

You said something like this in your first reply but made it about ballast resistors and totally lost me. This statement above tells me more clearly that if my msd was to die for some reason, I wouldn't be able to just "take it out of the loop" and hook the ignitor wires directly up to the appropriate (+) and (-) terminals of the e-core.... Which is something I would certainly try, not knowing any better. Maybe an e-core isn't the right thing for me. If the msd takes a dump I'd still like to be able to get back on the road again without spending too much time. My current setup has some nifty little jumper wires that allow me to bypass the msd wiring in about 5 seconds. I kinda like having this peace of mind.

Doesn't seem practical with an ignitor distributor and low-pr e-core coil. If my msd died I'd also have to swap in an oem type coil (which means having one handy) to avoid killing the ignitor.

The answers to nearly all your questions are contained therein. Including several optional scenarios. And all support information for these ignition-related components, including mixing and matching, specifications, and complete installation/wiring recommendations is contained in the support area of both the msd and mallory websites.

Only thing is, msd's documentation on mating their e-core blaster coil to a pertronix-equipped 1978 IH Scout is a little sparse.

Any form of ballast resistor or resistor wire is only used in a breaker point inductive ignition system or in conjunction with the true chrysler electronic ignition system introduced in 1969. No ballast system is ever incorporated into the installation of any cd ignition box, no matter what coil is used.

Then why did you guys bring it up? Mentioning it here is just confusing. It has no place in this discussion of cd ignitions, hall-effects, e-cores, etc. Tmi. Let us speak of ballast resistors no more.

The only reason the Ford-type tfi coil wiring scheme is shown is due to it's somewhat unique connection terminations which were designed to be quick and cheep to install on the vehicle production line, those have no performance advantage whatsoever. Replacement aftermarket coils for Ford apps are designed to use the same oem terminations since the average hobbyist...

Well actually, the only reason the Ford tfi is shown is because I chose to use that particular diagram, taken from msd's installation guide. I could have just as easily used the GM or chrysler diagrams, but the Ford tfi diagram seemed to be the simplest and resemble my IH wiring the best. And the msd's connectors will hook directly up to the coil, rather than having to use some fancy kind of pigtail. That, and I've heard they're cheap, reliable, and relatively powerful.

I don't have any idea what this stuff is you're saying about there being some big hype over Ford's coil. Maybe other people have given that impression, but I never said anything about Ford being great. I think you've read way too much into my posts.

But it raises the question, if they're all the same, then why not use a Ford-app coil? Couldn't you have just said, "okay, if you're using a Ford tfi coil, yes that diagram is correct."??

The spark plug boot remover you posted is the same ones I use in all my shop and travel tool sets, about $3 locally at any auto supply.

Awesome. Good to know. I'll look around for one. I doubt I'll find one for $3, but I'm sure it'll be less than summit is asking.

My personal opinion, the pertronix plug cables are nothing any different or "better" than anything else available as an aftermarket replacement part. Even the common house brand stuff from the big box parts houses are spiral-wound cable...

I think they're better for the simple reason that they work as well as everything else without looking stupid. They aren't a blingy red, yellow, or blue, and they'll snap in easily to my factory wire holders.

 

[Michael Mayben]

I guess you have answered your own questions then.

Sorry for suggesting that you educate yourself.

I'm done with this one.

 

[Patrick Morris]

I'm sorry if that turned out a little sarcastic. I was trying to point out--lamely perhaps--the problems I was having understanding your replies to my questions. Your knowledge of this subject is obviously vast, and your zeal to inform and introduce background information is, well sometimes that can be just what's needed, but it can also be a little... Confusing to a reader. This reader anyway. I guess I was trying to point that out in a round about way. Education can be a two way street. Written communication is my j.o.b. (I'm a technical writer. But I'm off the clock now so my prose might be falling short of the Mark.)

people are just people. Doesn't matter if they design backpacks or are software engineers. I've learned that if you try to throw too much stuff at them, go off on tangents, their eyes can glaze over. The goal is always to be clear and keep the reader... "happy" isn't the right word. At least mildly interested. If they loose interest or get confused, I'm not doing my job right. This applies mainly to official technical docs of course, less so to guys like us, on the forum banging away quickly at our keyboards.