need a SIMPLE answer for a TFI question

[Great Pharoah]

Aerocorey said.
"AAAHHH!!! I need coffee or something. I originally wrote this to disagree with GP, but he's right. I totally mis-interpreted what he said until I re read it like 3 times. I had never considered that running 12V at the coil coild hurt your module. That must have been a mess...

Bowtieman, if you go to an MSD box you will be switching to a CD style ignition. You won't use the truck's ignition wiring to power your coil, you'll hook the MSD box straight to the coil, and nothing else. It forces something like 500V into the coil."

Thanks Aerocorey, I appreciate that. You just made my day. I agree about the typo, I just think that the typo is here.

" In Ford’s original TFI setup, only 8 Volts are provided to the coil. However, there is some general consensus that the coil can safely handle a full (12 V) power supply. Your stock ignition module could very likely fail if you use the full 12 volts, so we recommend using only 8 volts. If you want to run it with the lower voltage like Ford did, then you would simply put a resistor wire (see the part numbers chart above) in between the coil and the (+) power source. We chose to run the full 12 Volts directly to the coil for maximum power output. This resulted in our stock (OEM) coil becoming uncomfortably hot, and we ended up swapping out our ignition module with a prototype for the Mutant ignition module that can run on the full 12 volts. We recommend either upgrading your ignition module, or using the resistor wire to reduce the voltage. You’ll want to study the wiring diagrams posted below until you are comfortable that you have found the correct wires to splice into before you hook up your system. Once you have found the switched power source, splice it into the red wire on the TFI coil plug connector. Splice one of the green wires on the TFI coil plug connector to the green wire that comes out of the ignition module. The other green wire is not required, and can be cut off, or it can be left for future use in wiring up a tachometer."

Change the word coil to module, and then it makes sense. And yes it was a mess, and some of the sealant crap is still sticking to the fender well, I learned the hard way on that one.

Jode, he said he was doing this to his 90, I was assuming the 90 has Duraspark from the factory. The article is a little ambiguous. I'm not sure what I would do with a truck that didn't have the Duraspark from the factory, but I think I would consider ZM's modified HEI dizzy, or save longer and go MSD all the way including the MSD dizzy, but that's pricey too.
GP

[jamsni]

What resistor? The factory setup does not have one, other than the wire itself. Are you maybe thinking of the capacitor (condenser) that is bolted to the coil bracket?

My bad, I am thinking of the capacitor. Aahh, electrical...

[jode]

Just a few thoughts. Yes, you can run the original wiring, the issue (and perhaps the confusion) comes in when you realize that not all OEM wiring in a FSJ is the same as any other FSJ. For example, if you were converting a non-Motorcraft equipped FSJ to a new distributor and the TFI system, you would need to go through the process of finding the right wires, and considering the use of the aftermarket resistor wire.
As stated, the OEM system in some rigs already runs a reduced voltage (through the use of a resistor) to the coil, so there would be no need to reduce it further by installing the Napa aftermarket one. In this case, Bowtieman should just use his original wiring to run less than 12V.
It looks like that article could use a bit of clarification as to how to install the upgrade to a later model rig.
Glad to hear you got it all sorted out with the help of all the folk here on the board.
I found that when i ran a full 12V to my coil, my IM heated up to an uncomfoirtable level. Eventually, after reducing the voltage to the coil with mixed results, I ended up upgrading the IM to an HEI module. That system worked great.

[GWChris]

Okay, am I reading all this correctly? The wire from the horseshoe cap that attaches to the can style coil is a resistor (one being power, the other for tach output)? Then what purpose does the resistor attached to the coil serve? I am also doing my upgrade, but from what I have read/been told is that the power is 12v but the resistor is what lowers the voltage. Remove the resistor, and it is back to 12v, right? I am doing the IM upgrade also but I was going to use the existing wiring as a switched power source.

What resistor? The factory setup does not have one, other than the wire itself. Are you maybe thinking of the capacitor (condenser) that is bolted to the coil bracket?

[jamsni]

Okay, am I reading all this correctly? The wire from the horseshoe cap that attaches to the can style coil is a resistor (one being power, the other for tach output)? Then what purpose does the resistor attached to the coil serve? I am also doing my upgrade, but from what I have read/been told is that the power is 12v but the resistor is what lowers the voltage. Remove the resistor, and it is back to 12v, right? I am doing the IM upgrade also but I was going to use the existing wiring as a switched power source.

[bowtieman55]

AWESOME! I honestly think the MSD 6A upgrade will be less confusing

THANKS YALL!!!

[aerocorey]

AAAHHH!!! I need coffee or something. I originally wrote this to disagree with GP, but he's right. I totally mis-interpreted what he said until I re read it like 3 times. I had never considered that running 12V at the coil coild hurt your module. That must have been a mess...

Bowtieman, if you go to an MSD box you will be switching to a CD style ignition. You won't use the truck's ignition wiring to power your coil, you'll hook the MSD box straight to the coil, and nothing else. It forces something like 500V into the coil.

[bowtieman55]

I will keep this thread, and all of yall in mind when it is time to upgrade the stock Duraspark module to a MSD 6A box (so I can run a full 12 volts)

[Great Pharoah]

I certainly appreciate EVERYONES input, but GP, you just took alot of stress off my shoulders. It sounds as though we are gonna have the same setup. I'm using the MSD 8227 TFI coil, MSD Cap-A-Dapt, and MSD 8.5mm plug wires...whew, I've actually gotten a headache from this and I haven't even started the upgrade yet

edit-so I guess I can return the ICR22 resistor wire unit to NAPA now?

Yeah, take it back, you don't need it. I have Accell 8.8 spiral core wires, great for spark, lousy for AM radio reception. The 90 degree boots are fun, I'll get straight boots next time. I'm using Bosch Super copper plugs gapped at 50. Beru Silverstones are the best plugs made, but I can't afford $15 per plug.
GP

[bowtieman55]

Yeah, ditto - is it the coil or the module you're worried about? I thought the issue is one of burning up the module by running the COIL at 12V, because the module has to switch the coil current with a transistor inside, and if the coil is running at a higher voltage, it puts more stress on module.

Chris, I've been concerned with the possibility of burning up the module. APPARENTLY, the factory wiring IS a resistor wire...so there should be no worries...I hope

[bowtieman55]

I certainly appreciate EVERYONES input, but GP, you just took alot of stress off my shoulders. It sounds as though we are gonna have the same setup. I'm using the MSD #8227 TFI coil, MSD #8414 Cap-A-Dapt, and MSD #35859 8.5mm plug wires...whew, I've actually gotten a headache from this and I haven't even started the upgrade yet

edit-so I guess I can return the ICR22 resistor wire unit to NAPA now?

[Great Pharoah]

Use the factory coil wire, it is a resistor wire, and you will get about 8 to 9 volts at the coil. Using a straight wire with 12 volts WILL make your Duraspark module so hot the the plastic sealant will melt and run all over your fender and the module will fry shortly after that. You don't have to ask me how I know, I've made that mistake. If you want 12 volts to the coil, either do the HEI module thing, there's a write on that, or get an MSD 6a box. I'm running with the factory wire and a Duraspark box and mine is fine. I am using the MSD TFI blaster coil, and I have a very hot spark.
GP

[GWChris]

Yeah, ditto - is it the coil or the module you're worried about? I thought the issue is one of burning up the module by running the COIL at 12V, because the module has to switch the coil current with a transistor inside, and if the coil is running at a higher voltage, it puts more stress on module.

[aerocorey]

I'm not sure why you'd want less than 12V going to the module. I've never heard of anyone burning up a module that way. I'm thinking "Your stock ignition module could very likely fail if you use the full 12 volts, so we recommend using only 8 volts. If you want to run it with the lower voltage like Ford did, then you would simply put a resistor wire (see the part numbers chart above) in between the coil and the (+) power source." may have a typo in it. Replace the word "module" with the word "coil" and it makes perfect sense. The last part of the sentence says to put the resistor between the coil and power source which would have no effect on voltage to your module.

[xupe45tgp]

I hooked mine up with the factory wire and took that resistor off that was on the old coil and the ICC1 connector and have had no problems