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Discussion Starter · #1 ·
I installed the TR upgrade a few months ago, and when i pulled the cap off today for some other problems, i saw this on the terminals...you can see where i rubbed them with scotchbrite to clean them up...those scorch marks aren't just on the surface - they go right to the bone...

the upgrade included the cap base, cap, coil, 8mm wires and my previous Bosch Pt plugs (which i replaced today with champions), and the plugs were gapped to 0.045...is this normal wear for this upgrade?
 

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Onlt time I had scroching on my terminals was when I had the cap on crocked and didn't notice it.. but you'd have posted with Cross fire issues I had all kinds of cross fire and it ran like crap if at all. besides that mine have been clean ever since...
 

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Discussion Starter · #4 ·
no cross fire as far as i could tell - either before or after the upgrade...it hasn't been running like it's just off the lot, but then it does have 200,000 kms (124000 mi) on it...everything was seated properly too...nice firm fit and all the screws and clips good and snug...
 

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I have the tfi and now a tfi with the MSD 6AL (way friggin cool upgrade!!) The low end idle is incredible!!! I haven't run it down the road yet, so I don't know the MSD will perform there, but as for the low end, AWESOME.

As for the scorching though, I had normal carbon buildup, but never had anything burning like that?? Not sure why it would be arcing like that for you. Just a SWAG here, but are your plugs and plug wires all in good shape?? Maybe not a good enough path for all that current to discharge at the plug....Like I said just a wild as* guess.
 

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Interesting - there shouldn't be any carbon there. The terminals and the rotor electrode are all metal, not carbon.
The only source of carbon would be the plastic - or oil fumes. The brass doesn't contain carbon, and the cap's center button (carbon) shouldn't be coming apart. The plastic shouldn't be getting hot enough to vaporize and re-deposit, and there shouldn't be oil flying around in there.

Maybe it isn't really carbon, just looks like it?
Can you get the black stuff to come off and mark your fingers like a lead pencil?

The only thing I can think of that could possibly cause a mark like that is if the coil wire was defective, a gap is limiting the voltage, or the coil isn't putting out enough voltage to start with. Low voltage can cause those components to run hot, as the current is high.

Have a look at the spark - let it jump to something - other than you. It should be a thin crisp bright blue color, not a fat red one. A fat red spark indicates low voltage. Low voltage can cause the secondary components to run hot, possible scorching the black marks. Brass can corrode to black.

If you are using the original Ford type module with the ignition resistor and the TFI coil it may be the low voltage culprit.
The TFI coil's designed to be used without a resistor to get full voltage, yet the Ford module needs the resistor to keep from self destructing - overheating. The original Ford type module is not compatible with the TFI coil. They will work, but not to the best they could. There's been lots of posts regarding overheating modules and module failures - mainly because of not using the ignition resistor.

 

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It did smudge off of the terminals with a bit of scrubbing. I always assumed it was a byproduct of the arc. I went from a horibly tired 304 with prestolite to the ford tfi, and the increase in performance was so huge, that I never questioned it.... It may have been that while it was running so much better than the prestolite, it was still not as good as a tfi setup can be.

Either way though, it was never enough buildup to worry me, everything worked fine until the engine finally ran out of compression and refused to run another day.
 

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The Prestolite ignition system is just barely an ignition system. Sometimes I think a 9 volt battery and 2 bricks would be better. So even set up wrong, most anything will out perform it easy.

In fact, Presolite is so bad - ignitions, alternators etc that you'd think that British guy "The Prince of Darkness" (Joseph Lucas) had something to do with it.

I've head that's why the British like warm beer - Joe Lucas designed their refrigerators.
 
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ALL POSTERS:

Are you running a resistor/resitance wire to the TFI coil?

I have been trying to get a real answer to this for a while, maybe you guys can put an end to this.


Call this a hijack if you want, but I am wondering if the resistor has any effect on the cap wear.
 

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Discussion Starter · #12 ·
i am not. the original instructions didn't say anything about it, so i didn't include it...i also couldn't find a diagram for my '90 258, so it was out with the old, in with the new, bob's your uncle, away i go.

of course, now the damn thing won't even start (though not related to the resistance wire)...
 

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it depends on what you started with.

on my 89yj the answer was no. there is no resistance wire and I did not add a resistor. but, that is because the ignition module has that functionalty built in.
 
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Buggy, this is the other thing that makes no sense to me. I have pored over all the diagrams I can find, and I cannot see how the resistance wire affects the voltage to or from the module.

When guys have posted up saying "I've burned up 3 TFI coils in a month" he's eventually told to run the resistor.

Last time I asked, someone said it was to protect the module from burning out. The diagram definitely isn't showing a circuit where anything other than 12V is being supplied to the module.
 

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sorry bren,
I blew it. it looks like a resistor wire is used. dang. All I got is my Chilton and can't find the electrical section of my FSM. but, Chilton shows that the solenoid or something is connected to the ignition switch and bypasses the resistor wire during starting. says there should be 5.5 to 6.5 volts normal.

so the question is, do you need it with the TFI coil. I would say yes. I wish I had a schematic of the duraspark module but I don't. so all I can do is guess. traditionally the resistor is used to limit the current through the coil.

this is important because the only other major contributor to limiting the current is the inductance and resistance of the coil.

too much current through the coil will burn it up and the switch in the duraspark. the switch in the duraspark could be an SCR or a transistor, i don't know.

I do know that it works fine with the current limiting resistance.

you do not need it if you are using an MSD to drive the coil.
 

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There are THREE different kinds of Ford modules, DuraSpark I, DuraSpark II, and TFI.

Dura I - like Jeeps use - uses a resistor wire to limit current - used with a coil that's designed to operate at lower current levels.

Dura II and TFI do not use a resistor or resistor wire, has a built-in current limiter to limit excessive current, designed to be used with the lower primary resistance coils, like the TFI coil.

When you run a TFI coil - it has LESS primary resistance, so MORE current flows through the primary. It's designed to take the higher current - and is designed to NOT USE A RESISTOR - it wants lots of current. They are equivelent to the GM HEI. They give a bigger charge - High energy if you will. The output voltage is higher, the output current is higher and the duration is longer = better spark. BUT - that high primary current also goes through the output transistors of the module. If you use the DuraSpark I module that's designed for about 1/3 the current, it frys. That TFI coil was designed to be used with the TFI module - nearly the same as the DuraSpark II module.

To use the older DuraSpark I module with the TFI coil you HAVE TO USE THE RESISTOR. Else it'll constantly overheat - but the effective power of the coil is greatly reduced - possibly even less than stock. The reason some claim it's better is because they had a problem with their old system.

On the other hand, the Dura Spark II module, and the TFI module is designed to handle the higher current - and the lower primary resistance of the coil - without a resistor.
Those modules have a current limiter built in - not a resistor, an electronic device to limit the current to safe levels.
Mixing high current devices with low current controls doesn't work very well. As an example, you can't use an ignition switch to operate your starter directly - your ignition switch operates a solenoid, which operates the starter.
 

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In reply to:

When you run a TFI coil - it has LESS primary resistance, so MORE current flows through the primary.

[/ QUOTE ]
given the same voltage, if the coil draws more current then it will put out more power. if the turn ratios are the same.
from my understanding the TFI has more turns.....
NP/NS = Vin/Vout

so the TFI will have a higher output then the stock coil. even if the stock stuff is in perfect condition.

the only question is the longevity of the ignition module.
 

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Correct - well sort of:
The output VOLTAGE is determined by the turns ratio.
The TOTAL POWER (Watts) is determined by primary current and primary voltage. (Watts = Amps x Volts.) Both in and out.)

So increasing primary current (amps) gets a stronger magnetic field going - more total energy getting stored in the coil. The more energy stored in the coil makes it possible to release more in the secondary - when it's time. The way they increase the primary current is lower resistance AND full 12 volts across it.
The magnetic field builds up rapidly and very strong. Once it's built up the module's current limiter comes into play, limiting the amount of current so the module and coil don't fry (the Dura I does not have that feature.) If that much current was allowed to flow until finally shut off (spark released) it would fry the coil - just too much current. And the poor old module has trouble switching it too.

The secondary has many many more turns than the primary. The voltage is essentially determined by the turns ratio between the primary to secondary. The output voltage is multiplied greatly. AND since there is a stronger, bigger, more energy filled magnetic field, there's more current to flow in the secondary == more total energy. So the spark is much thicker and much more powerful.

If turns ratio alone was adjusted - by only increasing turns ratio - as you increase turns ratio the voltage would go up but the current will go down proportionately.

The TFI when fed with the full 12 volts inputs much more power in the primary, then outputs much more as well.

The TFI ignition, like the Dura II, and the GM HEI, charge the coil during the time when the engine isn't needing a spark (dwell time.) They get it fully charged in about 4 milliseconds - then "throttle back" the charge and wait until it's needed. At idle there's plenty of time to charge the coil up, but at high RPM it doesn't have much time. That's why conventional ignitions run out of steam at high R's, they simply don't have time to fully charge the magnetic field. These HEI types get it charged FAST and BIG. They don't start to "Roll off" spark until way abouve 6000 RPM, where conventional types start rolling off about 3500.
Plus - with all that "power" in the spark (magetic field) but the plug gap is about the same, the spark duration is much longer. Conventional ignitions are about .75 milliseconds spark duration time, where these are about 2.5 milliseconds - nearly 4 times longer!
That means the spark is jumping in the chamber much longer, contacting more particles of fuel, starting a much bigger fire! (He He - Short match vs long match in your fireplace.)

I hope I haven't made things more confusing.

Test -- try touching a spark from a conventional ignition - you jump, even laugh about it.
Do it with a Dura I, TFI, or GM HEI - they downright hurt!
===== Power!

He He - now let me throw in a curve - for the electronic guys. All the ignition coils (except CD's,) both conventional and High Energy types - one side of the secondary is the output to the plugs, the other side is tied back to the high side of the primary. The bottom side of the primary is switched by the module.
That configuration makes it into an autotransformer, turns ratio calculations are no longer totally valid.
Calculations for an autotransformer are beyond my little mind! The turns ratio doesn't have to be as high - it multiplies itself.

Dura I vs Dura II -- Dura II connectors are slightly more squared looking - hard to describe - best way is side by side comparison - NO they don't fit. And the wiring sequence is a bit different too. Sorry, I don't have a wiring diagram for the II. Internet searches - most are the Dura I but called the Dura II - the diagrams I've been able to find on the net are wrong.

Maybe someone has the right one?
 
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