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-   -   TFI and HEI what's the difference? (https://forums.off-road.com/jeep-short-wheelbase/212450-tfi-hei-whats-difference.html)

82CJnLA 09-07-2005 10:15 AM

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?

Junk Yard Genius 09-07-2005 11:15 AM

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.

82CJnLA 09-07-2005 12:13 PM

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.

John_Strenk 09-07-2005 12:17 PM

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.

LEVE 09-07-2005 12:40 PM

Re: TFI and HEI what\'s the difference?
 
[ QUOTE ]
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!

82CJnLA 09-07-2005 04:21 PM

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

Junk Yard Genius 09-07-2005 04:31 PM

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...

82CJnLA 09-07-2005 04:51 PM

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.

John_Strenk 09-07-2005 05:22 PM

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.

OlllllllOCJ 09-07-2005 09:39 PM

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.

[img]/ubbthreads/images/graemlins/40BEER.gif[/img]
Dale

MarineOpLaw 09-07-2005 10:31 PM

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

[/ 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?
 
[ QUOTE ]
[ QUOTE ]
[...]
There is no emissions testing in Indiana, we wreck them first so it doesn't matter.
[...]
Dale

[/ 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]

[img]/ubbthreads/images/graemlins/40BEER.gif[/img]
Dale

86CJ7 09-08-2005 09:22 AM

Re: TFI and HEI what\'s the difference?
 
[ QUOTE ]
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.

TFI, HEI, DuraSpark, Hy Fire are all STILL INDUCTIVE IGNITIONS.
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...
ECT. ECT. ECT. ECT.....
THAT INDUCTIVE IGNITION ISN'T GETTING THE JOB DONE RELIABLY, PERIOD.
-------------------

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...
-----------------

Voltage:
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.

Amperage:
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.

Duration:
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?
 
[ QUOTE ]
...
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.

[img]/ubbthreads/images/graemlins/40BEER.gif[/img]
Dale

RRich 09-08-2005 09:46 PM

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

[img]/ubbthreads/images/graemlins/40BEER.gif[/img]
Dale

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

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

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.
IT DOES NOT.
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.

[ QUOTE ]
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.

[img]/ubbthreads/images/graemlins/40BEER.gif[/img]
Dale

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.

OlllllllOCJ 09-09-2005 06:49 PM

Re: TFI and HEI what\'s the difference?
 
Here's a comparison that John Strenk made between his "Stealth HEI" module and a Dura Spark module:

<font color="red">The DuraSpark at idle:</font>
http://www.dana60.com/76cj5/DuraSparkAtIdle.jpg

<font color="red">And the HEI Module at idle.</font>
http://www.dana60.com/76cj5/HEIAtIdle.JPG

Click either picture (same link) to read the thread on JU.

And then if you want to read more of John's adventures, this is a very good one (click it):

http://users.adelphia.net/~john.stre...put1800RPM.JPG

A few weeks ago for kicks I fired up an old o-scope, nothing nearly as nice as John's. After more fiddling with trigger inputs and crude pickups than I would care to go into.... I saw the same type results just not as pretty or easy to read due to the very old and uncalibrated scope.

[img]/ubbthreads/images/graemlins/applause.gif[/img] John Strenk [img]/ubbthreads/images/graemlins/applause.gif[/img]

While I still have some work to complete the project I intend to standardize the four Jeeps that end up in my driveway when broken to the "Stealth HEI" module with a few spares to carry.

[img]/ubbthreads/images/graemlins/40BEER.gif[/img]
Dale

Junk Yard Genius 09-09-2005 06:52 PM

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



For the little Jeep first...
I have a switch on the dash (have the HEI module there too.)
Flip the switch, go from HEI to DuraSpark without missing a fire sometimes...
(Watching on the laptop if I got a mag trigger and no coil fire)
DuraSpark factory resistor wire on the DuraSpark module,
No resistor wire on the HEI.
Diodes on both to keep from back feeding current either way.
I figure with resistor wire in place, and a stock canister coil, I'll get a better idea of what most of the readers are dealing with.
When I start collecting data with an E-core coil, I'll drop the resistor wire, or maybe test with it in place, then drop it...
Don't know yet, just have to see....

I have been doing silly stuff, like getting into a good pull on a hill and switching ignitions, or during a highway pass and switching.
Interesting results, somewhat confusing, but interesting.
-------------

The coil spark energy breakdown on the little jeep is probably the ignition coil, and the current reaching it. Small wires, resistors, age, Dumb****astan construction all lead to problems, and DuraSpark module (also discount store cheepie) breaks down about 1,500 RPM with total failure about 3,700 RPM.

The HEI isn't much better, spark energy breakdown using it to fire the same everything else is about 1,700 RPM with total failure about 5,700 RPM, but that's with no load.
I wouldn't be a bit surprised if either of them couldn't get the fire lit reliably beyond 3,000 RPM.
-------------

As for the MSD, you pretty much made all my points...

Multi fire in the RPM ranges most of us drive in, so full benefits...
Mine have been working fine for over ten years (probably more like 15) and I trust MSD.

With at least 600 volts going to the ignition coil, saturation times are at least 50+ times faster.
12 volts Vs. 600 volts is no contest in saturation times.

Standard 12 volt inductive ignitions are limited by saturation times, PERIOD.
They simply can't sustain reliable spark energies past a point that is about 1,500 on the standard V-8, a little longer (more saturation time for less cylinders) for 4 bangers or 6 cylinders, but around 1,500 RPM is normally when spark energies start to suffer.

MSD removes that obstacle, saturation times are faster than discharge times, so the little CD module has removed that problem.
Now the problem becomes how fast can you discharge the standard ignition coil...
It has to discharge before you can fire it again... And that is the limiting factor now instead of saturation times.
It really isn't a problem, when you can fire the plug 6 times in the span of time factory ignitions fire once, if at all...

Also, with 600 volts hitting the coil, you get MONDO more amperage!
The spark energy is so much fuller and richer (to borrow cooking terms! I am a fat guy after all...)

What you may want to watch is the time between MSD firings.
With the basic laws of thermodynamics, if you can fire the plug a SECOND time, or a THIRD time fast enough, you can take advantage of the heat 'Trail' left by the firing before.
(I can't think of the proper term for the residual heat...)

The first fire gets the area up to (and beyond) flash point, and if the second firing is fast enough (and MSD is) the second can take up where the first one let off,
IE: much shorter time to flash point than the first firing...
Not to mention MSD throws enough amperage at the gap to knock you off your feet, and it will fire a plug in a cup of oil.
(I've tried it, you can!)

With the heat and ion trail established, and so much more amperage going to the plug, the second and third, and fourth and fifth....
Firings are almost completely sustainable flash point burns, where the first one (and the ONLY one in a 12 volt inductive ignition) is almost entirely consumed just heating the flame channel up to flash point...
----------------

Let me ask you this...
Why do Supercharger manufacturers, CNG, LPG & other gas kit manufacturers, Alcohol conversion kit manufacturers all recommend CDI modules if not MSD ignition modules by name?

The fact of the matter is, Gasoline is the only fuel you can fire with a standard 12 inductive ignition even remotely reliably...
You can't even fire kerosine unless the engine is above 200 degrees (water temp), and that's gasoline's closest cousin!

Remember the old tractors and Ford cars and Trucks that has a gallon tank for gas to start the vehicle on, and a main tank for kerosine?
They usually had louvers in front of the radiator to block air flow so you could heat the engine up to kerosine temperature faster...

Ever worked on a mulit-Fuel engine?
Why do you think that when you switch over to kerosine the ignition switches off?
It's worthless, it isn't firing squat, that's why...

With MSD on the new military scout vehicles, they can reliably burn gasoline, kerosine (jet fuel), diesel, bio-diesel, alcohol and just about anything else you can pour in the tank!
(I've heard they can actually get sugar water to fire, the holy grail for multi-fuel engines...)
It's not your basic 6 series module, but the internals are pretty darn close!

RRich 09-09-2005 08:08 PM

Re: TFI and HEI what\'s the difference?
 
Good points on the CD. Remember the old tube type CD's used on Porsche?

Wondering - when you flip the switch from HEI to Dura, does the timing remain the same? There may be a variation due to the voltage threshhold levels needed to fire the HEI vs the Dura. The HEI triggers at a higher voltage, not as sensitive as Dura, good, and bad.

How are you handling the coil wire into the distributor? A "Y" configuration would tie the two coil's secondaries together, putting an undue load on whichever is running at the moment. One would absorb the energy from the other.

You said you are still using the round coil - no E coil yet with the Dura. If you are driving the round coil (to avoid the "Y" problem above) with the HEI that may be the reason the HEI's crapping out early. I don't know how the HEI likes the different internal resistance of the round coil - never tried it. With the internal current limiter and variable dwell it may not give the round coil enough charge.
And - you must have a pretty elaborate switch to switch in the resistor for the Dura, and none for the HEI.

Of all the HEI's I've tested and run on my or customers cars, the HEI did not even start to roll off at less than 6K. Something's bad wrong if it does.

Way to test roll-off - scope, unplug a plug wire - voltage should go up to about 40-42 KV, called Available Voltage. Of course if insulation is bad, or a bad rotor, it won't.
Rev it up, watching the Available Voltage, rev till it begins to drop significantly. Usually when it drops 10% is called the roll-off point. So if it was 40KV, then 36KV is the roll-off point. It still works above that, but does not have as much power.
I've found stock HEI's are effective to about 8K+. Beyond that they turn to mush.

Junk Yard Genius 09-10-2005 02:44 PM

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

Good points on the CD. Remember the old tube type CD's used on Porsche?


[/ QUOTE ]

Yes I do, but they took HUGE amounts of current to operate.
The only thing I liked off that ignition system was the ignition coils.
No Iron core, just wrapped around a foil tube. Discharge build times were nearly instantaneous, but duration wasn't that great.
Really helped with total discharge times though.
Still only one discharge per firing window...
----------------

[ QUOTE ]

Wondering - when you flip the switch from HEI to Dura, does the timing remain the same? There may be a variation due to the voltage threshhold levels needed to fire the HEI vs the Dura. The HEI triggers at a higher voltage, not as sensitive as Dura, good, and bad.


[/ QUOTE ]

That's one thing I'm wondering about...
I'm using a single distributor mag trigger (Chrysler), and switching it over.
I'll have to use a crank trigger for base line comparison if I really want to know how much delay is inhearant in the different systems... I just haven't fabricated a crank trigger yet.
(not a hard job, just a lazy man! And I've had other 'Irons' in the fire lately.)
I do know the trigger to actual firing time is increased when using the HEI (equivlent of taking advance timing out), but not enough to get bent about.

Like I said, I'm trying to collect data on what every configuration someone on the BBS might be running after the initial cap, rotor & plugwire upgrade, so I'm open minded...
I'll let the data tell me what's going on, instead of me trying to manipulate the data to fit a preconsived notion of what supposed to be going on...
------------

[ QUOTE ]

And - you must have a pretty elaborate switch to switch in the resistor for the Dura, and none for the HEI.


[/ QUOTE ]

Switch, 4 pole, double throw.
Default on both modules when NOT powered is coil ground OPEN. This helps.
2 for mag trigger switching, one for coil ground, one for module/coil power.
Modules are in the drivers compartment, so that helps with the wiring spegatti bomb.
Diodes keep power from back feeding on coil/module power legs at the coil.
Only ONE ignition coil and coil wire.

I do run seprate coils, and will run dual triggers and coils later, but right now I'm trying to keep it as close to stock as possible so I can figure out what is going on.
-----------------

[ QUOTE ]

You said you are still using the round coil - no E coil yet with the Dura. If you are driving the round coil (to avoid the "Y" problem above) with the HEI that may be the reason the HEI's crapping out early. I don't know how the HEI likes the different internal resistance of the round coil - never tried it. With the internal current limiter and variable dwell it may not give the round coil enough charge.


[/ QUOTE ]

I do expect the HEI is suffering with the factory round coil, but like I said, I'm trying all of the posibilities that readers might have, and that is certianly one of them.
I'll let the data tell me *IF* and *HOW MUCH* when the tests are done...
Pre-concieved expectations are not productive right now...

No where in any HEI conversion writeup did I see where it was MANDIATORY to change to an E-core coil...
(Oversight on someone's part,) So there is a VERY REAL POSSIBILITY there are several out there that followed the HEI articles, and still have the round coil.

And, there is the crowd like Dale writes about, that just WON'T spend the money...
And the crowd like the wrecked crew, that just won't follow directions no matter how well written or explained...

BTW, I don't have a real problem with one coil absorbing much spark energy...
the second coil isn't grounded unless it's ignition system is activated, so energy loss is minimal.
------------------

[ QUOTE ]

I've found stock HEI's are effective to about 8K+. Beyond that they turn to mush.


[/ QUOTE ]

If they were reliable to 8K, wouldn't all of the GM guys be using them in racing, instead of MSD?
8K would put them in NASCAR racers. I've never seen a HEI in a NASCAR...

What I've been trying to tell you, and illistrate to you, is there is a WORLD OF DIFFERANCE between winging the throttle in the driveway or garage bay, and actually running down the road or track or trail...

Setting in the drive way, you don't have all the lights, 105 accessories on, and water in the alternator... Or brushes in the alternator momentarily loosing contact with the sliprings when you hit a bump or rock, or the slip rings loosing contact when the engine rotates when the clutch is poped or the there is a big throttle movement...
That's why a battery elminator capicator won't work for a HEI distributor.
All of this affects input voltage for the HEI, not to mention the factory undersize power wire they use.

How about 70 throttle changes every operating minute.
That's what Bosch came up with for the average driver when working on fuel injection.
And I'm sure it's much more than 70 with a older vehicle on a rough trail or rough road...
That relates to 70+ different fuel ratio mixtures every minute that the ignition has to overcome.

How about moisture content in the intake charge?
Ever hit a puddle and have steam come out from under the hood?
Ever drive on a rainy day? How do you think moisture affects charge or just the spark in the chamber, not to mention every inch of the conductors & connections under the hood?

How about the residual exhaust gasses left in the combustion chamber with 70 throttle changes a minute?
When you are in the dirve way, with constant and smooth throttle changes, that exhaust flow isn't impeaded, and draft gets to play a big part in things...
You get pretty consistant fuel ratio numbers... Get off the shop floor, and things change!!!

They change so much that we need larger alternators, dual batteries, bigger tires, deeper gear ratios, ect...

I'm not knocking you for what you do/did in life, we all need diagnostic tools, but diagnostic tools in the driveway/garage bay and the real world don't often 'Play Nice'...
Just ask the current alternator that served my little '73 CJ-5 for 33 years...
Like Tim Allen says, 'Time for MORE POWER!'

86CJ7 09-10-2005 03:46 PM

Re: TFI and HEI what\'s the difference?
 
So what is the bottom line. All this technical info is really cool but would you notice a difference when driving with a HEI vs MSD vs Duraspark?

Junk Yard Genius 09-10-2005 05:02 PM

Re: TFI and HEI what\'s the difference?
 
If you have an '83 or newer Jeep with BBD carb, you *shouldn't * do the HEI module or you will defeat the on board emissions crap.

With my '73, you have to upgrade to an magnetic trigger to use either the DuraSpark or HEI.
The '73 was originally breaker points.
http://www.junkyardgenius.com/jeep/cj502.html

The '78 to '82 are the most likely candidates for the HEI module.
---------------

[ QUOTE ]

So what is the bottom line. All this technical info is really cool but would you notice a difference when driving with a HEI vs MSD vs Duraspark?


[/ QUOTE ]

Clearly MSD rules the day.
---------------

The facts in my mind are clear, MSD kicks ass on all common factory ignitions.
It's so much stronger that the test isn't fair...
When we compare DuraSpark to HEI, we are comparing Apples to Apples...
MSD is a CD or Capacitive Discharge ignition, so it's like comparing Apples to Beer, Steaks & Horny Prom Queens.

It's 50 state emissions legal, it will help your emissions.
Although it's not cheap, it's reasonably priced.

It works with all common ignition triggers, even points.
(Unfortunately, Jeep used an UNCOMMON ignition in the Prestolite ignition for about 4 years, depending on engine, from '74 to '78)
Replacement FACTORY distributors grow on trees, so this isn't a huge problem...

MSD works with all common factory ignition coils, internally resisted or not.
This makes it a GREAT item for us 'Mix & Match' types.

RRich 09-10-2005 06:15 PM

Re: TFI and HEI what\'s the difference?
 
Properly upgrading to either MSD or HEI you'll never notice the difference in performance between the two. With the HEI you'll have money left over for other things you need. Plus HEI parts are readily available and cheap.

Either will make a big difference in performance and mileage over any version of the Ford Duracrap, or Prestojunk.
If you are in a state where modifying the ignition is illegal, suggest you hide the HEI module in the old Ford box - Stealth HEI. Or use the CARB approved MSD.

86CJ7 09-10-2005 06:16 PM

Re: TFI and HEI what\'s the difference?
 
I have a hard time beleiving that a Jeep engine that rarely sees over 3500 RPM needs anything other than a stock or HEI ignition. I see the need for the biger distributer cap and rotor but it is not a race car. The HEI is easy and you don't have to mount the MSD box somewhere.

OlllllllOCJ 09-10-2005 09:14 PM

Re: TFI and HEI what\'s the difference?
 
[ QUOTE ]
I have a hard time beleiving that a Jeep engine that rarely sees over 3500 RPM needs anything other than a stock or HEI ignition. I see the need for the biger distributer cap and rotor but it is not a race car. The HEI is easy and you don't have to mount the MSD box somewhere.

[/ QUOTE ]

[img]/ubbthreads/images/graemlins/applause.gif[/img]

Thanks for saying exactly what I've been trying to put across. [img]/ubbthreads/images/graemlins/blush.gif[/img]

[img]/ubbthreads/images/graemlins/40BEER.gif[/img]
Dale

Junk Yard Genius 09-10-2005 10:32 PM

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


Well, I have a hard time believing that no one here can get that the biggest gains you can achieve with your ignition work is the MSD module...

I just can't seem to stress the point enough, MSD delivers it's greatest assets at the RPM you all are talking about...
Namely, 400 to 3,500 RPM.
My experience has been different than RRich, I routinely see MSD firing multiple times past 3,000 RPM.
Even if it fires one single time past 2,500 it's still a much hotter and sustained spark.

HEI if you want to, DuraSpark if you want to...
The Question was which one delivered the good best, and that would be MSD hands down.
DuraSpark and HEI aren't even LITERALLY in the same class as MSD.
----------------

If you are a cheep guy, use the factory DuraSpark...
If you are adventuresome or experimental type, use the HEI,
If you want the best in your given RPM range, use MSD.

I personally don't care what anyone uses... but I don't want to hear the sob stories and complaints later...

John_Strenk 09-10-2005 11:13 PM

Re: TFI and HEI what\'s the difference?
 
A side from the fact that the MSD is a capasitive discharge device I also think the multiple spark at low RPM is pretty neat.

Would there be any benifit to getting just 1 or 2 more extra spark per firing out of a Duraspark or HEI module a RPMs up to 2500 RPM. ??

I'm thinking of a Voltage comparitor for sensing the pickup and a couple of a 555 timer (556?)just to get 2 sparks out of a coil at each firing.

It looks like all you would have to do is pulse the Orange wire on the DuraSpark to fire the ignition module just like the ECU does on the 82 and later Jeeps.

The down fall of course is how fast you could saturate the coil each time. With a CD system you don't have to worry but with a coil it's slower. 2500 RPM would be like 5000 RPM in this case.

As long as you testing ignition modules why not add in Chysler? They have one that is as easy as an HEI or DuraSpark. Just 4 wires
http://static.summitracing.com/globa...cc-4120600.jpg
http://store.summitracing.com/defaul...=400122&Nao=90

Or
http://static.summitracing.com/globa...cc-4120534.jpg
http://store.summitracing.com/defaul...=400122&Nao=90

OlllllllOCJ 09-10-2005 11:15 PM

Re: TFI and HEI what\'s the difference?
 
[ QUOTE ]
If you are a cheep guy, use the factory DuraSpark...
If you are adventuresome or experimental type, use the HEI,
If you want the best in your given RPM range, use MSD.

I personally don't care what anyone uses... but I don't want to hear the sob stories and complaints later...

[/ QUOTE ]

Getting close.....

If you are a cheap (or cheep) guy use the HEI module with a TFI coil and the Ford larger Cap/Rotor/8mm Plug Wires. Best bang for the buck! Period. You also get the benefit of common parts that will be available at any parts store.

If you have a pile of Dura Spark modules (like I do)... Just use them... Who cares if you burn them up... They become "Stealth HEI" modules.

If you are the adventuresome or experimental type (with a larger budget then most of us), Go with the same parts that the Drag Racer and NACAR teams use. Actually some use Mallory Ignitions... But many use MSD. There's no question in my mind that a CD ignition works better but I can buy a new set of gears or half a set of tires or save a little more for that front locker that would be so much more fun.

I personally don't care what anyone uses either. But why in the world would they spend too much for an ignition system for a Jeep based on how wonderful it works in a RACE CAR!!!

All of these parts may have some short comings.... but they were built into millions of vehicals.... making them very easy to find.... and they are very reliable for a daily driver or weekend warrior Jeep.

MSD gives you a kickback? Or you just have some strange fixation?

[img]/ubbthreads/images/graemlins/40BEER.gif[/img]
Dale

John_Strenk 09-11-2005 06:30 AM

Re: TFI and HEI what\'s the difference?
 
MSD actually works and is [i]relitivly[/i} cheap compaired to what you can spend on a Jeep for an ignition system. Actually you can spen a lot more on a MSD but I'm to cheap to even explore the difference right now.

Look at the price of a Jacob'$ Computerized ignition that actually compute$ what you need for your next $park. And then look at the price of a DUI.

I've used MSD in all my racing application. But someone else was paying for it.

Maybe the home built, modified GM HEI distributor should be given a shorter acronym like DIY.

Junk Yard Genius 09-11-2005 10:37 AM

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


OK, now you have crossed the line Dale.


[ QUOTE ]

MSD gives you a kickback? Or you just have some strange fixation?


[/ QUOTE ]

No, I don't get a kickback, or anything from MSD.
(Other than a quality product at a very reasonable price)

The question was, What is the *Best* ignition for the money.
That would be MSD 6 series modules.
DUI, Jacobs, ect. are all much more expensive and don't do anything more (most do less) for your vehicle.

Although now that MSD's patent has run out on the original 6 series module design, you can purchase rip-offs at twice the price, all the while being touted as the 'Latest Thing'...
------------------

The Question WAS NOT,
What does some tight as guy that can't keep up in the conversation think?

If you have the 'Better Idea' we would ALL LIKE TO HEAR IT!
I'm the one that brought the Motorcraft large cap and rotor upgrade to the BBS.
I'm the one that brought the TFI ignition coil to the BBS.
Why do you think they call it the 'Team Rush' upgrade? Or did that one get by you also...?

I'm NOT the one that made a dime from the upgrade, although several people sold inferior parts and incomplete kits, I never made a penney.
It was a gift, a freebie to keep the people here from making the mistake of a $500 DUI-HEI or $500+ Jacobs ignition, which half of the conversations here were b!tching about the ignition systems when I arrived here.
And against all advice at the time, I gave it away instead of trying to sell a kit.
And I took a lot of crap from the short-bus crowd when I first suggested it, but now it's a staple...
It's even been ripped off (with no credits) by the 'Monster Machine' magizines...

Now some pinhead thinks I'm working for stickers from MSD?!...
------------------

CD MODULE IS THE NEXT LOGICAL & LOGISTICAL STEP...
(Nice job defending the world being flat...)
------------------

And don't try the argument that someone else would have come up with it...
You had from '76 to 2000 to do that very thing, and not one of you came up with anything but throwing money at aftermarket ignition systems that weren't any better than the factory originals...
24+ years passed, and all anyone did was throw money down the drain...

It was <u>ME</u> that came up with using OTC Ford parts, so <u>DO NOT</u> try and tell me what will and won't work correctly.
--------------------

[ QUOTE ]

All of these parts may have some short comings.... but they were built into millions of vehicles.... making them very easy to find.... and they are <u>very reliable for a daily driver or weekend warrior Jeep.</u>[/b]

[/ QUOTE ]

No pinhead,
If the factory parts were "<u>very reliable for a daily driver or weekend warrior Jeep.</u>", you would all be using the factory Jeep cap, rotor, plug wires, ignition coils, ect.

You don't listen, and you damn sure can't learn...
You also seem to have a real problem with keeping your mouth shut in situations you don't understand...
--------------------

Now, spout off with something lame that makes no sense and has no factual content...
(... flatulation will offen occur shortly after death and throughout the decompisition cycle...)

RRich 09-11-2005 10:43 AM

Re: TFI and HEI what\'s the difference?
 
You hit it on the head!
The reason you see so many MSD's on race cars is they are free! They pass them out like peanuts on an airline.
And - if you win and have enough MSD stickers on yor car, the contigency money is great! They want you to have the box prominantly displayed in the engine compartment - but it doesn't have to be hooked up, just look like it!


The Jacobs "computerized" ===== Smoke and mirrors!
They claim at certain times under certain conditions they "intensify" the spark.

There is no time ever, no speed, no load, no conditions where the spark needs to be LESS than full output, how can you intensify something that's aready full?

DUI is a very pretty nicely done rebuilt distrubutor - polished, plated -- pretty! But in order to make it work properly on a Jeep you have to take off the "racecar" weights and springs, replacing with bone stock HEI.
And, install an adjustable vacuum advance to get the curve to match your carb.
If you are into "pretty" go for it.

RRich 09-11-2005 11:04 AM

Re: TFI and HEI what\'s the difference?
 
John - yes the Chrysler box is simple.
But it is not a performance upgrade.
It's the same as using stock points without the points - or you can even trigger it with points if you want.

Chrysler went to it to help control dwell variations. Their distributors had the bushings close together, made excessive shaft wobble, causing too much dwell and timing varations. Had trouble passing emissions. The points put a side load on the distributor shaft, causing it to vibrate at certain speeds, driving emissions way up. The electronic box triggered by a magnetic pickup helped - no side load to speak of.

Performance wise - available voltage, rise time is the same as Pertronics, points or the stock Duraspark. Spark duration was even shorter than the others.

The modules were very reliable - best around, but the dual ballast resistor was very troublesome.

RRich 09-11-2005 11:34 AM

Re: TFI and HEI what\'s the difference?
 
TR - yes, test equipment rarely is able to "go along" on a test ride - the power cord usually falls out.

But the seat of the pants "yup, misfires" doesn't get it either. It's a combination of both, plus experimenting, guessing etc.

Often test equipment does not pinpoint the trouble either - doesn't always tell you what's wrong - but it usually does tell you what isn't!

Picture lying on a table while gasping for air - One doc says "Smokey" says it's the heart that does that. Another says Bubba's article says it's the lungs.

"It's OK TR, we have both in stock. We'll try one, then the other."

You'd suddenly become more of a believer in test equipment.

Hopefully you'll never have to face that.

Junk Yard Genius 09-11-2005 02:37 PM

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

That snapper-head chaps my ass...
Takes my upgrades, trys adding a HEI module, screwed that, and declares himself the last word in the subject.

This is the same guy that posted the nightmare of wiring that was installed so poorly I didn't even bother to comment...

Then questions my motives? Fuc$ him with a jackhammer...
He better hope we never meet face to face, or Lucy will have some 'splainin' to do...
-------------

as for 'test' equipment, put the ignitions system in an environment chamber, add two atmospheres, moisture, exhaust gasses oil vapor, liquid oil and liquid fuel, maybe some inorganic compounds fused to the electrodes, then we'll talk.

I have that very chamber, called the 'Crusher'.
The name should pretty much describe what happens to 'Theory' when the hammer falls.
You are in Cal, get a hold of Craig Railsback, head tech geek at Blower Drive Service and see what he thinks of the Crusher...

JeepDaddy 09-11-2005 03:14 PM

Re: TFI and HEI what\'s the difference?
 
I just bought one of these for my 304 for under $200 delivered:Proform HEI

I have the Prestolite so I didn't have much to upgrade. I haven't installed it yet, but it should work good.

jdoggmoney 09-11-2005 04:53 PM

Re: TFI and HEI what\'s the difference?
 
Used junkyard 6 cyl HEI -$25.00
Replacement Cap and Rotor -$30.00
AMC V8 Dist gear -$30.00
Ford 300 Plug wires -$22.00

Single wire hook up -Simple

Two years later, I've driven through more water than most in all tempurature extremes with no signs of skipping or missing.
My jeep leaps to life with the turn of the key every time.
I've gotten what I consider to be reliable spark from idle to occasional spurts of 4000rpm.

HEI and don't look back [img]/ubbthreads/images/graemlins/grin.gif[/img]


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