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MarineOpLaw 09-07-2005 10:31 PM

Re: TFI and HEI what\'s the difference?
There is no emissions testing in Indiana, we wreck them first so it doesn't matter.

[/ QUOTE ]

Hey Dale... I thought they <font color="brown"> rusted away</font> first in your 'neck o' the woods'?

[img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/neener.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]

OlllllllOCJ 09-07-2005 10:41 PM

Re: TFI and HEI what\'s the difference?
There is no emissions testing in Indiana, we wreck them first so it doesn't matter.

[/ QUOTE ]

Hey Dale... I thought they <font color="brown"> rusted away</font> first in your 'neck o' the woods'?

[img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/neener.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]

[/ QUOTE ]

Well yeah.... they rust away. But only if some nit whit doesn't wreck the darn thing.

I just happen to keep my junk in the garage most of the time and actually know how to drive. Two skills most Hoosier's don't seem to have. [img]/ubbthreads/images/graemlins/confused.gif[/img]


86CJ7 09-08-2005 09:22 AM

Re: TFI and HEI what\'s the difference?
wel im putting funds together to upgrade my '82 cj with the carter bbd.

[/ QUOTE ]

I have a 258 distributer with the Teamrush big cap upgrade, MSD wires, MSD 6A, Tach adapter, blaster coil, wireing adapters. All of this stuff has about 500 miles on it. Should be everything you need. I will let it go cheap, If interested PM me.

Junk Yard Genius 09-08-2005 09:04 PM

Re: TFI and HEI what\'s the difference?
OlllllllOCJ / Dale, LIGHTEN UP!
This ain't pIRATE 4x4, we're all friends here... [img]/ubbthreads/images/graemlins/blush.gif[/img]

BTW, Good search info in your post! That just about covers everything!

Do you know how many times I had to post the Original Ignition upgrade when I first started out here five or six years ago?
Or how may times I've been asked the same 4 or 5 questions?
This is a new experance and a BIG STEP for some of these guys just starting out...

When I first started out here...
Everyone was spending $500 (or more!) bucks on Jacobs junk, getting little or no customer service and having to pay for what should have been warranty work...
(in Jacob's defense, they are getting better about things since the company changed hands...)

Or the dreaded DUI HEI...
There is a piss away $400 of your favorite dollars!

All just so they could have larger caps, better plug wires, ect...

It was so difficult to get anyone to believe that just a few dollars worth of off the shelf parts could make the stock Jeep ignition run with the high dollar bunch...

And the fact that it was all bolt on, with no modification...
That made a lot of people think it was too go to be true...
No one really accepted it until someone put together the parts and started selling it online...
Once you hang a 5X price tag on it, they started believing it...

What I still don't understand is the big move to install a HEI module.
With the cap, rotor, plug wires and coil upgrade, the factory DuraSpark ignition is getting the job done as reliably as can be expected, and (arguably) better than most ignitions would.

It doesn't matter which inductive ignition you use, it's still a 12 volt inductive ignition...

12 volt inductive ignitions give you ONE (1.0) chances to fire the cylinder, and if the input voltage to the coil is low, or the fuel mixture is overly rich/lean, or not atomized properly, or if the piston/rings aren't warm, expanded and optimizing compression, or if there is excessive moisture in the air (cold weather/fog/rain) or if the plugs are gaped even a little oversize, or if your engine is getting on in years and has a little oil fouling in the cylinder...

The best deal going on modules is the MSD 6 series module.
It's a True Capacitive Discharge ignition, and it just blows the inductive ignitions off in the weeds!

I know there are several here that for what ever reason don't like MSD...
But the fact of the matter is, MSD delivers 100% to 1,000% increases in useable spark energies, and does it in the lower operating RPM ranges, from idle on...

More amperage, more voltage, more spark duration, the three areas of spark energy that regular factory ignitions can't hold a candle too...

More voltage means you can fire the plug with a wider gap.
Fire the plug with carbon, liquid fuel or water/oil fouling.
Fire the plug with dense moisture content (foggy days or with water injection).
Fire the plug with todays extra lean fuel ratios.

More Amperage means a 'Hotter' or 'Richer' spark.
That means the spark can burn away fouling.
Ignite lean fuel mixtures.
Ignite overly rich or poorly atomized fuel/air mixtures.

MSD delivers around 1,000% more duration of spark, the actual time the spark lasts in the gap of the plug.
MSD does this by firing the plug several times very quickly with a very hot spark, making sure your cylinder actually fires and produces power, instead of being a dead player and a burden on the rest of the engine.

ANY output from the cylinder is preferable to being a drag on power for the rest of the cylinders...

Once you do the cap, rotor, plug wire, coil upgrades...

If you just want to 'Tinker' with your ignition system, by all means, do the HEI module.
You will gain experience, confidence and you will learn something.
You may also be the First, or maybe the ONLY guy in your group with that particular modification...
And for about $20 for the module, and a few bucks in wire and terminal ends, it's a pretty good way to learn about ignitions.
(Don't forget to supply that module with a power relay and some 10 AWG wire!)

If your Jeep is running fine by your standards, and you don't see any reason to 'Tinker' further, then by all means, STOP!
If it makes *YOU* happy, then that's all it has to do!

If you want increased horse power in all ranges, increased torque and pulling power, increased fuel mileage, cleaner emissions (a real biggie for some of you!), and a cleaner running engine, you may want to consider a $150 MSD module...

OlllllllOCJ 09-08-2005 09:33 PM

Re: TFI and HEI what\'s the difference?
You do have a strange ECM location since it's a 1982 and I don't know what that does to the wiring harness. Maybe John can help with that since there's a thread on JeepsUnlimited on the subject.

[/ QUOTE ]

OK, I did a search on the JU Forum. Take a look at this:

<u>Does an 82 have an ECM?</u>

Only guessing but would expect that the wiring is the same as 1983 - 1986 years just located in a different place. So the wiring diagrams might be good to go for you.


RRich 09-08-2005 09:46 PM

Re: TFI and HEI what\'s the difference?
"""""MSD delivers around 1,000% more duration of spark, the actual time the spark lasts in the gap of the plug.

Since the HEI's spark duration is 2.25 MS - then 1000% longer would mean 2250 MS, or 2.25 seconds long. Hopefully the engine turns faster than that.
MSD has it's advantages yes, but not that much.

The "multiple" spark stops being "multiple" at about 2000 RPM. It "runs out of breath" at about 6000 RPM, about the same as an HEI. Use a distributor machine to compare.

Even the MSD website admits it.

OlllllllOCJ 09-08-2005 10:46 PM

Re: TFI and HEI what\'s the difference?
I won't type the same thing five or six times TR/JYG/Aaron, there is just no reason to do it. A couple simple links and it's up to the reader to click on it and actually read it.

As for searching... I do that pretty well since it saves me daily with computer issues and the crazy world of Microsoft. That's just my life I won't wish it on anyone.

As for DUI HEI.... My opinion: Way over priced but very functional. Use quality wires with it and set it up correctly it will work fine. The advance curve won't likely fit well for an old Jeep (or Toyota FJ motor either). Find a stock HEI distributor that all you need to do is change the drive gear - good Jeep upgrade.

In general (again my opinion): There's no need for a "True Capacitive Discharge Ignition" on a limited budget running 20 + year old Jeep motor. Even that cost too much for me.

The large Ford cap, rotor, 8mm plug wires are marvelous on a 258 if you do nothing else. The motor will start better and run smoother. Now that is assuming that you don't have any other problems to muck it up.

Add in a TFI coil.... Even with the resistor wire in place.... and again it will be just a little easier to start and slightly smoother running. RRich likely won't agree with that but it has been my experience with my two 258s. And that is where I stopped on my CJ-7 (so far).

"Grumpy" my poor old neglected Scrambler had bypass surgery and the "Stealth HEI" implant well after the Ford cap/rotor/plug wire change. I don't think that there is a lot of difference but it now runs a full +12V to the TFI coil. We don't call the darn thing "Grumpy" without cause, it still needs some serious Carter BBD procedures to be as healthy as it should be (I digress).

So why do a TFI/HEI Hybrid?

The Dura Spark ignition modules are getting harder to find and cost about $30 where the HEI module it's self is only $16 or $17, add a few connectors and some of your time it's an easy replacement that can be found in any backwater parts store on the shelf.

I carry spares.... but....

If you walk into an Auto Parts store in Attica Indiana on a Saturday morning asking for a Dura Spark Module... The reply will be "I can have that for you on Monday afternoon". Then again if you ask for a HEI replacement module... You walk out with one and wheel some more after lunch.

Should something bad happen to your MSD, while maybe not very likely it could happen, can you pick up a replacement in Podunk KY? Yes I know you can keep your original ignition as a backup.

Remember we are talking about Cheeps here.... Cheap people with Jeeps. [img]/ubbthreads/images/graemlins/blush.gif[/img]


Junk Yard Genius 09-08-2005 11:48 PM

Re: TFI and HEI what\'s the difference?

Since the HEI's spark duration is 2.25 MS - then 1000% longer would mean 2250 MS, or 2.25 seconds long. Hopefully the engine turns faster than that.
MSD has it's advantages yes, but not that much.

[/ QUOTE ]

The entire discharge EVENT lasts 2.25MS...
The ACTUAL USEABLE DISCHARGE is about 0.35 to 0.39ms, depending on coil design.
DISCHARGE EVENT includes ramp up time, discharge, and osculations cycling after the actual discharge...
Common misconception that the ENTIRE firing cycle produces useable spark energy.
Plus, the actual spark starts weak and 'thready', a stray trail of electrons ionizing gasses along the way, then useable spark energy and ends the same way as the discharge runs it's cycle and becomes a stray trail of electrons again.
ALL of that trail of electrons, no matter how weak, is considered 'DISCHARGE', even though it wouldn't make a hair on your arm stand up, and doesn't have a chance in hell of firing the thick atmosphere in a combustion chamber...

You also have to consider how long it takes surrounding fuel &amp; air to reach combustion temperature (thermodynamics: radiated thermal transfer to a <u>sustained</u> flash point)
Often times USEABLE SPARK ENERGY is long over before <u>sustained flash point</u> is ever reached.

The "multiple" spark stops being "multiple" at about 2000 RPM. It "runs out of breath" at about 6000 RPM, about the same as an HEI. Use a distributor machine to compare.

[/ QUOTE ]

There are two parts here...
1. My Jeep spends most of it's life between 600 RPM and 2,500 rpm, so my Jeep (and everyone elses) gets it most benefit from the MSD module.

Multiple fire doesn't stop at 2,000 or 2,500, just less of the multiple fires because as RPM increases, time for multiple fires decreases...
Not that the module can't supply the discharges, just that the engine isn't spending enough time at the correct window Before TDC for as many discharges to take place.

2. The reason for no multiple sparks after 5,500 to 6,000 RPM is simply that there isn't enough time for multiple fires at elevated RPM's.
The Single discharge is much longer and stronger than any inductive ignition can provide.

3. The Capacitive Discharge unit used in the 6 series module can charge (saturate) the ignition coil a BARE MINIMUM of 50 times faster than ANY HEI module, so there is NO POSSIBLE WAY that a HEI module could keep up with a MSD module at any RPM.
The HEI module can't even switch fast enough to keep up with MSD's saturation times, not to mention the coil can't DISCHARGE fast enough...

4. I have NEVER seen a stock style HEI module that could sustain acceptable spark energies above about 1,700 or 1,800 RPM, and total ignition breakdown occurs around 8,000 RPM on the best units.
HEI can fire a stock, low performance, next to no compression, overly rich beater engine for a while longer, but raise the compression, thicken the atmosphere, lean out the mixture and open up the plug gap, and the HEI sucks wind FAST!

Add water injection, a supercharger or turbo, nitrous, decent compression or lean out the mixture to make power, and the HEI is totally useless.

I have PERSONALLY tested, and raced MSD modules at up to and exceeding 15,000 (thats 15K RPM) with out failure, and that's with factory style ignition coils, over the counter plug wires, factory mag trigger distributors, and over the counter premium grade distributor caps &amp; rotors.
(AGAIN, totally off topic for Jeep owners, and no Jeep owner here is EVER going to turn over 7,500 RPM and mean it!)

5. There are NO distributor machines available to turn a distributor at 15,000+ RPM.
I use a digital triggering device (for accuracy), and fire the modules ON THE VEHICLE using a test plug(s) for visual verification, and an 'O' scope for patterns and firing voltages.
By testing on the vehicle, there are no questions about what losses or gains *MIGHT* be happening... Or what *MIGHT* be better for that particular vehicle...

Second part...
I have two ignitions on this little Jeep I just bought...
One is DuraSpark, one is HEI.
I'm also going to do comparative testing on a MSD 6 series when I'm done with the factory inductive discharge ignitions...

The factory DuraSpark module breaks down about 1,500 RPM on this particular Jeep.
The factory HEI module breaks down at about 1,700 RPM on this particular Jeep.
Via a laptop and interface, I've been tracking the trigger/fire delay, dwell, input voltages, appx. firing voltages, current draw, engine temp., exhaust temp and O2 content, ect. ect....

This was the perfect test bed, as it needed to be rescued from breaker points hell when I brought it home, and while I was installing the ignition, I just added the thermocouples, transducers, inductive pickups, ect...

If you are even in the slightest interested, I'll let you know how things turn out when I get further along...

OlllllllOCJ 09-09-2005 12:11 AM

Re: TFI and HEI what\'s the difference?
Uhhh Um.... Cheep! [img]/ubbthreads/images/graemlins/ooo.gif[/img]

Don't get off into anything that requires more than a good solid fire at somewhere below 3,500 RPM and it's got to be CHEAP!

To argue over crap that costs more than 99.9% of us are willing to spend will be lost on deaf ears.

Every dragster and NASCAR race car has two MSD Ignitions.... WE DO NOT NEED THAT.

It don't matter what fails at 8,000 RPM because a 20+ year old 258 will toss all of it's internal parts outside the block well before it gets there.

Read the thread again.... front to back, then we can argue based on my very limited experience.

I'm still chillin' here.


RRich 09-09-2005 11:04 AM

Re: TFI and HEI what\'s the difference?
TR - We've been through this before.

If you have access to an automotive ignition analyzer that can measure the spark in a time base - not all can, Sun cannot,- or lab scope, you can measure/see actual "burn time." That's the horizontal line right after the ionizing spike, before the oscillations.
That's the actual time the spark is jumping across the plug gap - hopefully starting a fire in the chamber (kinda like holding the match under the log.)
That's actual ignition time, not to be confused with the entire fire/intermediate, and recharge time.

Remember the ignition has to fire the plug, then "quick get ready" for the next plug's firing - it has alot to do in a short time span. The Kettering ignition types, including HEI, Dura, and points, the energy is built up in the magnetic field in the coil.

CD's like MSD, the energy is built up in the capacitor, the coil is used simply as a transformer. Still, "burn time" - the time spark is actually jumping across the gap is just as important. The fuel particles don't care where or how the spark got there, just that it's there.

Stock points type "burn time" is about .75 ms long at idle, stays that way until the coil saturation time is the limiting factor - around 3000, then it quickly rolls off.
Dura is about the same, as is Pertronics etc.
Stock complete TFI is about the same as HEI (but it's a POS!)

HEI is about 2.25 ms at idle, the limiting factor for burn on those isn't so much coil saturation time, but the available time between cylinder firings. At higher speeds it has to recharge the coil in order to be ready to fire the next.

If you look at the MSD with your scope, you'll see that the multiple firings stop around 2500, not way up there. Easy enough to see, try it.

Trying to fire the plug several times like MSD does certainly can help an old tired engine pass emissions (if that was the problem to begin with, as it's more likely to get a fire started. The HEI, although hotter than stock, still only tries once.

But, even above where it stops being an msd, the MSD still is a CD, so rise time - the time it takes to ionize all the gaps and "begin the spark" is faster, even faster than the HEI - much faster than a Ford's anything or points.

On your Jeep you said the Duraspark breaks down at 1700, I think you've mentioned you have the TFI coil on it? But you still have the resistor? Try something, see if it doesn't raise the breakdown point - try jumpering full 12 volts to the top of the coil. The module will run hot, so will the coil, but it should raise that breakdown point - unless the spark's jumping out where it shouldn't.

Once you get the MSD and the HEI as a switched circuit it should be interesting to do the comparison as far as actual driving it. I've done it, but not as an easily switchable system. Drive it, bring it back, covenrt it, drive it again - you lose something by not doing it right after the other.

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