Oh ya, checked the old plugs as we pulled them and all were nice and tan. #4 and #7 were a litttle on the white side, but not scaley. I'll see if I can get some pictures if anyone is interested in "reading" them.

 

[ QUOTE ]
.....Hit the clutch, and she rev's with no problem, back in Gear, she ran like crap.

[/ QUOTE ]

Interesting...I wonder if this has anything to do with the problem. I'm not entirely sure what it might be, but this may be something to look into.

 

[ QUOTE ]
[ QUOTE ]
.....Hit the clutch, and she rev's with no problem, back in Gear, she ran like crap.

[/ QUOTE ]

Interesting...I wonder if this has anything to do with the problem. I'm not entirely sure what it might be, but this may be something to look into.

[/ QUOTE ]

You might have something there. I first assumed it was just that it was taking the load off the engine allowing it to rev.

But....

Didn't you (Brent) have a loose bellhousing a while back. Acting like the clutch was way out of adj. ?

No chance you pinched a wire when you tightened it up?

Or
I have had this. Pushing in the clutch actually creates a better ground between the engine and the body/frame.

Do you have to push the clutch in enough for it to release or will some light pressure do it.

How about in neutral with the clutch OUT. Will it still rev up?

Just a few random thoughts.

 

Neutral w/ clutch out it revs fine and idles fine and and and.. put a load on the engine and it starts running like cap.

I did consider Clutch last night but Dave and I ruled that out.

 

Could be something there. How 'bout the grounds?
2 grounds - engine to battery -- probably good as you don't have a cranking issue - but check anyway. But also a good ground strap from body to engine is needed. The clutch linkage may be the body's grounding path.

The ballast resistor -- unless it's an intermittant problem with it -- very rare - not likely. But - the TFI coil in combination with a stock type module is asking for trouble. The TFI coil primary draws considerably more current than the stock coil (primary resistance is less) - forcing the module to carry more than it's designed for -- even with a stock resistance ballast resistor (which limits the effectiveness of the TFI coil.) May not be the trouble --- yet.

As far as totally eliminating whether it's fuel or ignition, do the "Propane Trick" - do a search on past posts. When it runs bad, simply add propane as a substitute for the carb's gas -- if it suddenly runs better - it was a fuel problem for sure. 30 seconds and you know which direction you have to go in.

 

[ QUOTE ]
Could be something there. How 'bout the grounds?
2 grounds - engine to battery -- probably good as you don't have a cranking issue - but check anyway. But also a good ground strap from body to engine is needed. The clutch linkage may be the body's grounding path.

[/ QUOTE ]

Yep, Good Ground from Battery to engine

Body to engine wouldn't do anygood as I have Fiberglass.

Also doesn't matter if Clutch is in or out it's whether or not there's a load on the engine. Clutch out in Neutral, runs fine, Clutch in in gear, runs fine, Clutch out in gear runs like A$$.

[ QUOTE ]

The ballast resistor -- unless it's an intermittant problem with it -- very rare - not likely. But - the TFI coil in combination with a stock type module is asking for trouble. The TFI coil primary draws considerably more current than the stock coil (primary resistance is less) - forcing the module to carry more than it's designed for -- even with a stock resistance ballast resistor (which limits the effectiveness of the TFI coil.) May not be the trouble --- yet.

[/ QUOTE ]

Rich, does the TFI coil need a full 12 volts? and What iginition module would be able to handle it. These modules are teh same as Ford Mudules that run the TFI, so what gives with that. I've never been able to get a straight forward and consistent answer on if the TFI can handle or does need a constant 12 volts, and if the Module can handle not having the ballast resistor. if not, what Module can I use?

[ QUOTE ]

As far as totally eliminating whether it's fuel or ignition, do the "Propane Trick" - do a search on past posts. When it runs bad, simply add propane as a substitute for the carb's gas -- if it suddenly runs better - it was a fuel problem for sure. 30 seconds and you know which direction you have to go in.

[/ QUOTE ]

only does it while driving so how can I supply Propane to it while doing this?

thanks Rich, keep it coming and I'll see if I can keep up with you

 

Brent, just brain storming here.

Can you check the current at the plug wires, making sure you have the correct volts/amps/or whatever? ..... you may have an "iffy" connection between the "battery to key" or "key to coil"

It still sounds like a vacuum leak to me, did/can you check the vacuum with a meter?

Do you get any back-firing when engine braking?

 

[ QUOTE ]
only does it while driving so how can I supply Propane to it while doing this?

[/ QUOTE ]

search ..... it's in there

 

I did search, didn't come up with anything other than doing LPG conversion.... help?

 

That new search function is a$$!!!!!!

Be sure to send Dirt Dog a nasty p.m. about it.

 

Propane Trick

 

weird.. I searched "Propane Trick" and never saw that one...

thanks aaron..

at the internet...

 

Brent sounds much like a weak fuel pump. You running mechanical? Oil smell like fuel?
Sometimes, they will seem to work OK at idle and even revs, but under load they stumble.
HTH, keep me posted, good luck!

 

[ QUOTE ]
Sometimes, they will seem to work OK at idle and even revs, but under load they stumble.

[/ QUOTE ]

Wouldn't there be enough fuel in the bowl to delay any results of a "slow" pump until after a hard acceleration was almost over, and not show up as soon as load is put on the engine?

 

Yes, there should be enough fuel in the bowl to delay the stumble, but if it's already marginal, that delay may be too short to feel.
Do the propane trick - under load - while driving it. When it falters, quick open the propane valve, hold the bottle upside down to get liquid. The propane will burn just like fuel - if for any reason it was stumbling because of lack of fuel, it'll pick right up. That will cover pump, filters, carb etc - anything that's keeping it from getting fuel. (And the valve set-up is handy to have around anyway.)
Obviously if it isn't fuel, then it wont help. But it eliminates playing with the carb and fuel system more. We can't always know what's wrong, but it helps to know what isn't!

You did change the coil wire -- I hope!

TFI ignition. Yes, the TFI coil is designed to run on a full 12 volts to get the high output. But it's not that simple. It's also designed to take that full 12 volts for a SHORTER PERIOD OF TIME. Else it cooks.

Basics -- the output voltage is a funtion of the applied primary voltage. At full 12 volts it will have an output of about 40 KV.
At about 8 volts, - using a resistor, it will be less -- 8v/12 = 2/3 meaning the output will be 2/3 of the norm, or about 27 KV.
The stock coil in stock configuration is about 30 KV -- MORE than the TFI coil conversion. Hmmmm.

So -- the obvious answer to get the voltage up to where it should be (40kv) is to eliminate the resister. The coil output will be like it should be - plugs get happy because voltage is up.

BUT -- now the poor little stock module has to switch on and off about twice the current it was designed for. (The TFI coil has less resistance, coupled with it's now getting 12 volts, current flow in the primary is at least doubled.) Poor little guy overheats and quits. Sometimes as he dies he gets intermittant. Module's not happy.

Plus -- the TFI coil is designed to take the current from the full 12 volts, but for a SHORTER LENGTH OF TIME. Dwell is charging time, or time that the coil has this high current flowing in it.
The TFI module that was designed to be used with the TFI coil has both a variable dwell AND a current limiter -- to protect the coil from overheating.

BUT -- the stock module has neither!
The result is the stock module is not happy since it has to carry all that extra current, and the TFI coil isn't happy because that current is there for too long a time.

It's not practicle to use the TFI module with the TFI coil as a conversion for a Jeep.

Some do use the TFI coil, some with resistor, some without -- but sooner or later they find out what happens.
You will find lots of folks that did it that way will swear it made it run better -- sure -- it can -- but when they did it they already had a problem with something else they never fixed. If you look hard you can find some that did it when they didn't have a problem before - and said it did not make any difference. Of course replacing a defective component with one that isn't makes a difference!

The guy that came up with that TFI coil swap scheme didn't understand ignitions. Part of it he presented was good - but not his idea. We've been swapping in the big caps ever since they came out. The bigger cap affords more dielectric strength between towers. But swapping in a coil that will have those troubles isn't so good.

But -- there is light - a very easy way.
The GM module is made to handle that low primary resistance, made to handle the high current, made to handle a full 12 volts applied to the coil, has the built-in current limiter and has the variable dwell. And they are cheap and easy to install instead of mixing and matching parts that will prove unreliable!!!
There is even a current thread on this subject right now. You'll love it!!!

The Ford TFI was Ford's attempt at trying to come as close to the GM ignition performance as possible without patent infringement. The coils look and mount different, but electrically they are nearly identical.

But, before changing the entire system, try the propane.
And -- if it does not help, I'd like to see you test the exhaust before swapping in more stuff. Let us know, then we'll step you through the exhaust tests.

No need to get more than one problem at a time -- the risk you take when swapping stuff around.

It's findable and curable, just takes a little time sometimes.

 

thanks Rich, I'll give it a test and let you know the outcome.

btw, that's the most straight forward and easy to read explanation of the TFI coil and Jeep Module I've read yet. thanks again.

It does leave me with one question, I thought the module that Jeep used is the same as Ford used??? I guess not from your post.

 

in the 70's and 80's jeep used 2 different types, prestolite and duraspark. the duraspark is the ford unit and my preference. you apply 12v to the module and use the associated coil that hooks directly up to the module and your done.
as far as your stumbling goes, sounds like the vacuum advance is hooked to the wrong port on the carb or the dashpot has a leak.
the miss is ignition, weather you have some bad components or a bad ground. i have heard horror stories about glass tubs for that very reason.

 

Totally agree -- the Prestolite is pure trash!

Jeep did use the Ford modules --.
A distinction needs to made too -- there are 3 types of Ford modules used in the 70's and 80's - on Fords.

DuraSpark (I) -- by far the most common. The same one Jeep used. 28-32 KV, .75 ms spark duration -- just like the old points systems. No real change except dwell no longer varied as much and lower maintenance.
Negatives: Subject to overheating, unreliabiity, intermittant operation - especially the earlier years (1975+). And, imported knock-offs were prevelant - even used the Ford & Motorcraft symbols on the aluminum module housing - those did not include the starting circuit that retards the spark during starting. That led to many startng difficulties, lawsuits, and finally government intervention.
Also due to the module's sensitivity, it false triggered to radio stations and CB radios - spurious RFI. Lots of ground straps had to be used on those vehicles using it - even the exhaust pipes, and lower control arms had grounding straps.

DuraSpark II - second generation Ford module - primarily used on the smaller V8's. Identification was the 2 plastic connectors were more squared looking and had one more wire, but they appear very similar -- they do not interchange with the original DuraSpark. Features were 40kv, different coil - still round, but different resistance, still oil filled, still had lots of iron core. A full 12 volts to the coil (no resistor,) module had the current limiter and varable dwell like GM. Module's aluminum box looked exactly like the original DuraSpark - just slightly different connectors. This was Ford's first attempt at controlling emissions with a hotter spark - like GM had been doing for several years. It was almost as "hot" as the GM except for the rise time - it was slower. The only failure it had was it too was unreliable, subject to overheating etc. And it too was subject to RFI.

Both the above systems had the ground for the ignition system in the black wire at the distributor. Both types often had the module mounted on plastic inner fenders, grounding the module was not necessary. But -- the black wire in the rubber grommet at the distributor was a big trouble spot. The crimp inside the grommet corroded from the acids in the rubber. Official TSB fix - cut the black wire and ground it solid to the vacuum advance diaphram screw.

The third, and best, was the TFI system. The module was a tiny Thick Film Integrated circuit mounted directly on the distributor. The magnetic pick-up coil was replaced with a Hall Effect device. The square shaped coil no longer was oil filled and had less iron in it (just like GM had been doing for years with the HEI.) That enabled the coil to "dump" it's energy faster, increasing the rise time of the spark. (The iron core slows down the reaction time.)
It too used the full 12 volts, no resistor. The output specs were a duplication of the GM HEI -- finally! And they were very reliable.
They got around the RFI problem with ground straps all over and shielded wires to the module.
The difficulty in using the Hall Effect pick-up makes it too complicated to adapt to a Jeep. It would require machining to adapt it -- not worth the effort.

But, using the best of both worlds makes a very sweet ignition system -- a GM/Ford hybrid! The larger cap and rotor from the Fords gives much better ability to resist flashover inside the cap (the terminals are farther apart.) That's a physical thing. The only thing to be cautious of is the outside top -- keep it CLEAN! The hot spark is directly underneath - it tends to flash through to the dirt on top - blowing a hole in the cap!

The pick-up coil inside easily triggers a GM HEI module - mounted remotely. The caution on that module is it generates lots of heat, make sure it's got a good heat sink.

The TFI coil (square) works great with the GM module - totally compatable. The DursSpark II coil (round) would also work, but the rise time would be slower, thereby losing one of the great benefits.

Combining the big cap, TFI coil, and GM HEI module creates an ignition system rivalling the best racing ignitions. You'd have to spend probably $2000 for a Direct Ignition to get the same performance. But when you light the fire inside the cylinder properly, how can you light it better?

Next step would be dual plugs -- anybody?

Hope this clears things up.

 

[ QUOTE ]
DuraSpark II - second generation Ford module - primarily used on the smaller V8's. Identification was the 2 plastic connectors were more squared looking and had one more wire, but they appear very similar -- they do not interchange with the original DuraSpark. Features were 40kv, different coil - still round, but different resistance, still oil filled, still had lots of iron core. A full 12 volts to the coil (no resistor,) module had the current limiter and varable dwell like GM. Module's aluminum box looked exactly like the original DuraSpark - just slightly different connectors. This was Ford's first attempt at controlling emissions with a hotter spark - like GM had been doing for several years. It was almost as "hot" as the GM except for the rise time - it was slower. The only failure it had was it too was unreliable, subject to overheating etc. And it too was subject to RFI.

[/ QUOTE ]

And this is the module I'm running. 2 plugs, 6 wires, one with Red and White, the other with Black, orange, Green and Purple. With that said, it should be able to run without a resistor correct? and handle a full 12v constanlty?

Risk of Over heating and RFI interference understood too.

One thing I noted on the TFI/HEI combo is that the HEI Module uses 5 wires, where as the Duraspark II uses 6. If I do go that route, I didn't see what it said to do with that extra wire that would go to the Green Wire on the Duraspark.

 

well, I bypassed the ballast resistor at lunch today since that's something I was able to do at htis time. WOW what a difference, I found all kinds of power I haven't had in a long time!

Granted that keeps taking me back to something Rich said already about people doing this....

[ QUOTE ]
-- sure -- it can -- but when they did it they already had a problem with something else they never fixed.

[/ QUOTE ]

Seeing as the new module has a lifetime warranty, and I carry the old module with me, I want to run this set up for now and see if my issue shows up again. the 40 minute drive to BBills shop tomorrow should be a good test. and yes Rich, I will see if Bill has the stuff to do the propane trick tomorrrow. I'd be interested in setting up and trying the test just to do it. sound interesting!

Thnks for all the tech info, I certainly learned more from reading these two threads than I knew before about TFI/HEI/Ignition, etc.

thanks, I'll keep you posted on resuts, now hopefully this thread can die a peaceful death.

 

Sorry I can't tell you the wire colors on the DuraSpark II - or even the original DuraSpark. Jeep never used the DuraSpark II - never did. So if you have the original wiring, it's the Original DuraSpark, not the II. The II squared connectors won't fit, preventing interchanging modules. They do look similar, you almost have to put them side by side to see the difference. (Or with a scope you can see the diff from across the street.)

You may just have a resistance trouble in the ignition wiring - harness, even the ignition switch.
I should have thought of it before - use a voltmeter -- (+) side of the coil. Key On, Engine Off it should read around 8 volts. Running it will be a little more - 9-10 nvolts?

Without the resistor it should read the full 12, running even more - charging system voltage.
Could it be possible there's two resistors in the circuit - one resistor wire in the harness and one external one? Stranger things have happened!

You may even want to run wires into the cab so you can monitor that voltage (with the original resistor hooked up.) Drive it till it gives trouble - quick, look at the voltage. Should be interesting.

But since it's better now with the full 12 volts I think you've found it.

 

[ QUOTE ]
But since it's better now with the full 12 volts I think you've found it.

[/ QUOTE ]

I don't want to be too hasty and say ya it is the problem. I hope it is, I'm still skeptical on if I'm covering up another issue just by increasing the volts. May very well be another resitor in the harness that I've not seen yet. the PO did some wierd things wiring this harness in here.

 

Measuring the voltage at the coil (the way it was hooked up) will instantly tell if it's got 2 resistors. Normal should be 8-9 volts, 2 resistors will read less, maybe around 5?
While reading the voltage, jiggle the key switch - if the contacts are bad - resistive - the voltage will jump around at the coil.

Kinda related but funny - lady came in - complaint was every time she made a left turn it would die. Starts right up afterwards. Several test drives wouldn't confirm it.
Turns out when she left the car with us she just left one key. But her heavy key ring would swing enough to turn the switch off on left turns! Duh!!!

Just shows most troubles are simple -- just hard to find -- we make them hard.

 

[ QUOTE ]
Jeep did use the Ford modules --.
A distinction needs to made too -- there are 3 types of Ford modules used in the 70's and 80's - on Fords.
...

[/ QUOTE ]

Great stuff... I'm saving this thread and hope that you don't mind if I use what you have written here... Will be sure to have you review it.

I would assume that you noticed my idea about putting a web page together. If not please look back at this thread:

V8 TR TFI HEI Upgrade Completed Another winner

I welcome everyone to help if they can and most especially RRich to help keep it technically and historically correct. No one's setup or ideas are beyond the scope as long as it's not injected (that's a different project).

My idea is to provide some simple and cost effective ignition upgrades for every Jeep we can think of that did not come off the assembly line with injection and computer control. Trying to take into account budget and difficulty factors in doing the modifications.

Opps

End of thread hijacking.

Dale

 

Maybe an explanation of WHY doing this conversion is preferred.

Most stock Jeep engines have trouble revving much over 3000 -- IF they can even do that. 2 major reasons - the biggest one is they "run out" of ignition. Also carburation and breathing are considerations.

This addresses the ignition:

A stock points type Kettering system puts out an available voltage of 28-32 KV (Kilovolts.)
When it fires a plug with an normal gap of about .030, the spark burns for about .75 milliseconds.

The Prestolite is hard put to even do that.
The original Ford DuraSpark does about the same as stock points.
Most aftermarket ignitions do about the same as the DuraSpark -- despite advertising claims. Easy to prove!

The Ford TFI ignition, and the GM HEI ignition have much more energy.
1. The available voltage is about 40 KV - that the total open circuit voltage - not jumping to anything. More voltage is created by the increased turns ratio. Watch out -- there are lots of aftermarket claims that say their GM coils can put out 50, 60, even 90 KV. Bull!!!! Easy to prove too.

2. The burn time on the same plug is much longer -- above 2.5 milliseconds -- meaning the spark is present for more than 3 times longer - far more likely to get a good fire started -- especially on today's leaner mixtures and not so volatile gasolines. More energy has been put into the coil when it charged, so more is available longer qwhen it discharges into the plug.

3. More current - fatter spark, more surface area to make contact with the fuel. Higher primary current - more energy, more output current.

4. Ability to jump farther - larger plug gap - more contact area too. Higher available voltage means it can jump farther across a larger plug gap.

5. More voltage at higher RPM - roll off is above 6000 RPM, where others roll off starting around 2500. Higher energy again.

6. High R's still maintains spark - still works at 8000 RPM, where conventional ignitions quit (but so does the Jeep engine usually unless built for that.)

7. And -- the rise time -- the time it takes the voltage to rise up from 0 to whatever it needs to be is about 4 times faster than conventional ignitions. It's akin to using an impact wrench - you can have a stuck bolt that 100 ft lbs won't budge - but "hit" it with the 100 lbs and it spins right off. Rise time is increased by the fact there is not as much iron in the coil's core. The iron is needed to store the magnetic field, but since more magnetic field is pumped in the the higher voltage and current, less iron is needed. The iron slows down the "dumping" of the magnetic field, slowing rise time.

All the above contribute to more efficiency, more power, better mileage, and lower emissons. Most will even notice starting is easier. Obviously if you burn the gas in the engine, we don't have to breathe it.

Doing a hybrid GM/Ford ignition is using the best of both systems.

If you don't believe this has more energy -- simply hold onto a plug wire from a conventional system. Now try the same with the HEI or TFI. If you live through doing the latter, you can tell us about it. (Don't try it please.)

Enjoy!!

Note: The MSD ignition operates on a different principle, it's a true CD ignition. It too is a good system.