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post #1 of (permalink) Old 09-07-2005, 10:15 AM Thread Starter
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TFI and HEI what\'s the difference?

happy humpday forum...i keep coming across the terms HEI and TFI. what's the difference and what is preferred? cost-wise and performance?
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post #2 of (permalink) Old 09-07-2005, 11:15 AM
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Re: TFI and HEI what\'s the difference?

HEI is High Energy Ignition.
Brand name for GM's E-core coil ignition.
Rotor too thin and too close to the grounded internals of the distributor.
Coil in cap arrangment has a slew of problems getting spark energy to spark plugs where it belongs.

Good points are,
Male terminals on cap (look like spark plug terminals), instead
of Female terminals (socket type, collect crud, never seal and there has never been an acceptable connector made for them that doesn't loosen up almost immedately.)

Easy to install, although you should add a ground wire to the distributor housing and to the heads.
Add a power relay with 10 AWG. wire that comes directly from the battery or starter battery terminal.

TFI, Was Ford's idea... (putting the ignition module in the distributor)
Thick Film Intergration. It was a flop.
The TFI ignition system did produce two things that are very good... Ford FINALLY went to an E-core coil, and it is excellent.
Ford finally got away from the DuraSpark ignition module.
The TFI module was a flop, but they moved on.

Ford cap, cap adaptor, rotor, plug wires & E-core ignition coils will interchange with '78 to '90 Jeep distributors with
no modifications to the distributor or ignition module.
Only a coil connector is required.
All tune up parts, all can be done by beginners.
Serious increase in reliability, driveability, economy and emissions.
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post #3 of (permalink) Old 09-07-2005, 12:13 PM Thread Starter
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Re: TFI and HEI what\'s the difference?

so in other words both crappy but still an improvement over the stock jeep ignition setup. i thought hei was supposed to be a good setup.
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post #4 of (permalink) Old 09-07-2005, 12:17 PM
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Re: TFI and HEI what\'s the difference?

Well compaired to stock either sytem seems like a $500.00 improvement when you go with one or the other.

In my book there is probably better ignition systems but I realy don't need it on a 258. I'm happy with the TFI hybred right now. Sure I'm not getting maximum spark out but it starts every time and runs great in a 29 year old jeep.
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post #5 of (permalink) Old 09-07-2005, 12:40 PM
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Re: TFI and HEI what\'s the difference?

so in other words both crappy...

[/ QUOTE ]

IMHO that's a bit harsh. Both systems have limitations, like any product does. If you use the system within it's bounds you'll be happy with it. As example, I've had a GM HEI on my 258 of over 9 years without a failure. I can't say that about the OEM ignition system.

You could easily buy Jacobs or MSD systems for a whole lot more money. Each of these ignitions have it's limitations and advantages which are unique.

But then look at the dollar invested and the payback. The GM HEI or the TFI ignition (or the hybridization using FOMOCO/GM/MOPAR parts) gives you more reliability, and the option of using off-the shelf parts as well as easier diagnostics when repair is needed.

These parts can be gained so inexpensively that it's almost a free upgrade. Then you can use your money for more important stuff, like root-beer floats!
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post #6 of (permalink) Old 09-07-2005, 04:21 PM Thread Starter
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Re: TFI and HEI what\'s the difference?

how about this?
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post #7 of (permalink) Old 09-07-2005, 04:31 PM
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Re: TFI and HEI what\'s the difference?

Yup, what they said...

The Best advantages of the 'TeamRush' upgrade of the stock Motorcraft/DuraSpark ignition Jeep used is it's all off the shelf tune up parts.
For the price of a cap, rotor, plug wires and ignition coil, you can have an ignition system that when you start it on cold or wet mornings, it starts and stays running.
You can now go down the road at highway speeds and NOT get used as a speed bump.
The Jeep can not only pull it's self, but a small trailer!
You can pull out in traffic with out wondering if you are going to be road kill before the ignition decides to cooperate with the rest of the engine...

The stock ignition system from '78 to '90 used a Motorcraft distributor and a DuraSpark module, both from Ford.
The screwed up using the short rotor, small distributor cap with socket or female connectors, and crappy low energy plug wires.
Do the upgrade,
You switch over to the tall rotor (keeps your spark energy from going to ground inside the distributor housing)
The distributor cap adaptor (gets the distributor cap up and away from ground),
The Large distributor cap (keeps the spark energy from going to the wrong plug terminal)
And that large distributor cap has better terminals (male or spark plug type terminals)
Now you can use late model High Energy spark plug wires with the good terminal connectors.

If you want a little more kick, use the later model E-core ignition coil from the TFI ignition.
They interchange with the system, but you will finally have to cut a wire... You will have to change coil connectors on the harness (two wires clearly marked).

This solves all the problems the factory screwed up on in getting the spark energy to the spark plugs, and is mandatory no matter what module you intend on running...
From '78 to '90 it's all off the shelf Ford stuff, and it fits right on your Jeep with no modifications.

All of this is mandatory before any high powered module is used, or you will just throw spark lots of places it wasn't intended to go...
You can't hang a high power module on the crappy small cap, short rotor, and outdated plug wires and expect it to work correctly...
And there are companies that will be GLAD to charge you an arm and a leg for over the counter parts... We are just saving you that money, so you can spend it on something you really need...( Like root beer and Cheetos)

If we knew what engine you were looking into upgrading, Year of vehicle, number of cylinders, we could give you exact part numbers...
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post #8 of (permalink) Old 09-07-2005, 04:51 PM Thread Starter
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Re: TFI and HEI what\'s the difference?

great info. wel im putting funds together to upgrade my '82 cj with the carter bbd. it's kinda strange but i guess it's an early cpu unit but it dosent run through the firewall as i've read on the numerous nutter bypass articles.
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post #9 of (permalink) Old 09-07-2005, 05:22 PM
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Re: TFI and HEI what\'s the difference?

You can still do the bypass. You just need to hunt down the wires from the distributor pickup to the computer. Infact it's probably easier cause it's not hidden behind the firewall.
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post #10 of (permalink) Old 09-07-2005, 09:39 PM
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Re: TFI and HEI what\'s the difference?

Since this subject comes up every month or so... I find it impossible to believe that absolutely nobody has suggested using the search function and doing your own research.

And then there is the fact that it's not the first time you asked pretty much the same question.

<u>'82 cj7 ignition question.</u>

"RANT ON" It looks to me like you just post up a question and then don't read the replies or follow any of the links provided and surely don't try to use search to find other threads. Could be that just bothers me more than it should. "RANT OFF"

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.

Start with this page that gives part numbers for the Ford large cap adapter, cap and rotor. You will also find different part numbers for TFI coils and even spark plugs. Be sure to change over to the 8mm plug wires, I really like the Motor Craft set.

<u>Ford Ignition Parts</u>

The distributor cap adapter, cap and rotor are a direct fit with no modification required - just a screw driver. I would suggest dielectric grease.

You can run the TFI coil by simply wiring it in place of the old coil using the coil harness in the part numbers. Here's where we will have some discussion about the TFI coil running at less than full voltage due to the resistor wire.... bla bla bla.... It will work, might be better other ways... It will work.

I have four Jeeps to deal with, all are 1983 to 1985 vintage originally with Dura Spark ignitions.

One is a 304 and the other three are 258's.

Everyone of them has the Ford cap/rotor and plug wires from that parts list.

The 304 has been running an Accel full voltage coil (no resistor or resistor wire) and a Dura Spark for the past five or six years. It will get a TFI coil and HEI module at some point.

Two of the 258's are running John's Stealth HEI with full voltage to a TFI coil.

Then there's my CJ7, has a TFI coil but not only is the resistor wire still in there so is all of the crazy plumbing that was originally built into it. The ECM still controls the Carter and even the spark. Vacuum advance is still manifold sourced. It has overdrive and will run 31" tires @ 70 MPH on the highway for hours then go trail riding often revving over 3,000 RPM and then turn around and drive for hours home (several board members will be happy to confirm that).

The typical reason stated to do the Nutter bypass is that the motor wouldn't rev above 2,800 or 3,000 RPM without bogging down. But if everything is working correctly, NO VACUUM LEAKS and you spend some time tuning it 3,500 RPM isn't a problem (likely higher if you trust your 20 year old motor that much).

Here's the famous Nutter Bypass info:

<u>The Ignition Bypass</u>

<u>John Nutter explains how he improved performance by modifying his Jeep CJ-7 ignition system</u>

<u>Pre-1983 Ignition</u>

<u>The "Nutter" Bypass with the HEI Ignition Upgrade for the AMC 258</u>

If you go the TFI coil/HEI module hybrid route you will need to disconnect the ECM (aka Nutter it).

Likely no one here can tell you how to get away with that in California, but maybe. I'm betting that if it's running well it will pass testing. Aren't the standards lower for older vehicles? The guy doing the test likely wasn't born when your Jeep was made so how the heck would he know what it should look like?

There is no emissions testing in Indiana, we wreck them first so it doesn't matter.

Back to USE THE SEARCH! (or just click on the links below):

<u>Anyone done the TFI upgrade on a 401?</u>

<u>Stealth HEI added, What the heck? Mystery Solved!</u>

<u>Rough Running continued...</u>

<u>258 TFI Upgrade Question</u>

<u>My attempt at the HEI conversion</u>

<u>V8 TR TFI HEI Upgrade Completed Another winner</u>

<u>Prestolite to Duraspark Distributor Swap</u>

<u>Timing with TFI Upgrade</u>

<u>Rough idle when cold, Air/Fuel?</u>

A few of those threads are about V8's... you might think that isn't related. It is.

Other threads are about problems and how they were solved, read those twice.

That's just the tip of the iceburg... But... If you have looked at every thread above and still have some questions.... post em up (just be sure to use a couple of those threads as a reference).

I still might just do my own search and post a few links that cover your new question.... so save me the time and try that first.

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