some of this to you.. I might get into a little bit of spark 101 but I'll try not to.

Your first question is about Ford having a larger diameter dist cap. Larger isn't better! Unless you have more rpm and the spark in the smaller cap is jumping to the wrong plug wire.. Which is zackly what happened to the Ford engines. So they fixed a problem we don't have.

I guess you havn't been hearing what we have said. Coils may have the POTENTIAL to make more pressure than the factory coil.. BUT no coil makes more voltage than it NEEDS to jump across the gap in the plug. If our coils make the spark at 3500...SO DOES YOURS! Yours may have the capability to jump a .090 gap where it can use all that potential.. but in our rides it CANNOT use that potential.

Yes we can put the larger cap on our engines.. but WHY would we if what we have now will NOT be improved on.

Then you ask about several things.. The point of your question (as I read it) is that YOUR setup will fire where ours will not.. The examples you give aren't anywhere near correct.

For example you seem to think your ride will fire in a flooded chamber that ours won't.. Here again you are incorrect. If the chamber is so flooded that our spark doesn't occur..and the electricity is carried to ground by the wet spark plug.. SO WILL YOURS! A wet plug will carry anybodies coil pressure to ground without making a spark...period.

Most guys are taken in by using something new and different.. But they don't completely understand how a coil works. The coil starts making electricity and keeps making more and more until it can discharge across the plug gap. Since the gap is a static size ALL coils will make the same spark across a gap that they can jump across. No coil will make a "hotter" spark. No coil will use more voltage..

Oh yeah you seem to think your coil won't jump to ground on wet or failing wires and the stock one will.. C'mon Marty get it together. Electricity will go to ground in the shortest way possible. No matter which coil you try to swap out..bad wires are bad wires and wet wires are wet wires changing coils won't help anything.

Now there IS a reason to swap and get a different coil.. Find a YELLOW one. Yellow looks better under the hood.

Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

Ps. I just reread your post. You seem to think the Ford dist cap will be more reliable, put out less emissions and save fuel.. You are totally incorrect you your assessments.
By installing the ford stuff properly on your Jeep..The Jeep will NOT know you did anything.. You will have everything zackly the same..unless you didn't do the install properly..
BJ

I still stand by what I said. I've seen the improvement and better reliability first hand.

I've been a Jeep dealership all areas-Level 4 Master Tech specializing in tune ups, emissions issues, driveability and electrical; ASE (A-1 to A8 + L1) Master multi-recertified tech, and CA certified smog technician since the early '90s and I understand ignition theory quite well. Rich mixtures, especially those that don't quite wet the plugs, are harder to fire than proper mixtures and require more voltage to light. Leaner mixtures are even harder to fire as I stated in an earlier post. The larger gaps permissable with the higher voltage FACTORY TFI coil will fire leaner mixtures better than smaller gaps with the can coil will. Almost any newer model car with that I can think of runs at least .044" gap, if not much more as opposed to the .035" gap that's stock on older Jeeps. Why do you think that is? Why did they go to .035" gap from the .025 gap on the points cars? The larger gap with higher potential voltage capability to fire it reliably IMPROVED the driveability, emissions, power and fuel economy! Yes, as I stated earlier, if your rig is currently running properly, and you don't ever operate it with deteriorated parts, or with extra-ordinary demands and you don't mind re-tuning it every time it misfires, you will see little improvement in emissions, power fuel economy. If you want your parts to be more modern, with longer service intervals between maintenance, and you don't mind opening the gaps to take advantage of the greater potential, you will see an improvement over the life of the parts. If they last twice as long between services, maintaining the designed power, emissions and economy that's an improvement, right?

For those people that don't change their plugs as often as they should, the higher voltage, larger cap, thicker silicone wires can handle the higher voltages needed when the plugs are worn, without misfiring. I recently tuned up a '89 Ford 5.0l truck at work that had 100k on the stock plugs and original wires (both dated '89), with gaps worn to .080" (from .045") and not have a misfire or driveability issue. (I'm catching up on alot of overdue maintenance at the fleet I'm working for now <img src="/forums/images/graemlins/rolleyes.gif" alt="" /> ).

Crossfire can come from the advance curve and is accentuated by any distributor indexing errors. (TSB's for small cap 4.0l Jeeps with crossfire issues show you how to check and correct the indexing). Factory Mopar EFI is not HEI but it does use the better plug type terminal, but with the old type 7mm wire jackets. Higher voltages possible with the FACTORY TFI COIL will make crossfire more likely if used with a narrow cap. Yes, I agree the main reason for the wider cap was to prevent crossfire. The wider cap has less chance of allowing crossfire from that point, as you correctly stated. The better insulated, thicker, wires also induce less voltage that can cause crossfireing external to the distributor. Any crossfire results in at least bad misfire or backfire, or worst case a broken piston. So you agree that this is an IMPROVEMENT to the old parts, right?

The added reliability from the new style cap comes from the spark plug style connections. As opposed to the old style, 1930s design terminal wells in the caps that tend to trap moisture, build corrosion and sieze to the wire terminals if they don't fall out on their own. An improvement, right? I don't see ANY modern vehicles with the old wire terminal wells in their coils (Most don't even run a distributor anymore) There must have been a reason, right?

The TFI coil is not even necessary to perform most of the reliability upgrade, In fact, the wide cap '82 300 Ford truck six spec'd out the same regular can type coil as the '80's Jeep 258, even the same Motorcraft part number. Wire sets for the 300 Ford (and some brands of the V8 sets) come with coil wires for either the can coil or the TFI coil. (later 300's went to the TFI coil with a spark plug type terminal, same low RPM engine).

The main benefit from running the TFI/HEI coil is the larger possible plug gaps ability to fire leaner mixtures This is the reason Ford and GM invested MILLIONS in new design ignition systems, to fire leaner mixtures more reliably (AT LOW, street RPMS), reducing emissions and adding fuel economy. Remember that the '80s were when the new mandated economy standards came into being, along with much stricter emissions standards. The manufacturers also had to warranty that the car would pass emissions without ANY maintanence for a very long period compared to the old days.

The Ford TFI coil costs a couple bucks less (new, in the same grade of parts) than the old can coil.

Factory Ford type silicone jacketed 8mm wires with silicone boots will last much longer than the original AMC/Jeep 7mm black wires, especially with high underhood heat and in moist salt air environments, such as we have here on the coast. The old wires' jackets and boots deteriorate much faster to the point that on a moist morning, or after driving through a puddle, they allow voltage to leak and cause a misfire or stall if the coil wire is involved. Yes, both wires will arc out if deteriorated, it's just that the better wires don't deteriorate nearly as fast! An improvement, right? Especially since the usually only cost a couple bucks more than the black wires, and are usually cheaper and more readily available in "resume speed Iowa" than aftermarket silicone sets made for the AMC/Jeep engines.

All that said, I don't even like Fords! <img src="/forums/images/graemlins/patriot.gif" alt="" />

I'm hittin' the rack, good night <img src="/forums/images/graemlins/sleeping.gif" alt="" />

You know all this talk of greater reliability etc.. is fine and all for someone who doesn't wrench on their vehicle. For those of us who do, a TFI upgrade is nearly pointless, and will have the effect BJ and SD are talking about. Even if you were to do the mod, the increased fuel economy would never be noticed if the carb isn't rejetted and tuned.

Doing a TFI as a bolt on upgrade for more performance is a waste of time unless the carb is tuned for a lean cruise rich power mixture.

If you want bolt on power the best thing you can do is get a TBI or MPI fuel injection kit. These kits come with a more efficient fuel delivery system that is tuned to make smooth clean power at all speeds and loads. EFI addresses off camber choking, hard start when cold, automatically adjusts mixture at different altitudes, better emmissions etc... Basically all the nuances of a carburetor will be eliminated.

TFI will give a reliability increase. But if you maintain your vehicle, you won't have a performance increase with TFI alone. Bolt on performance increases come in the form of EFI, Camshafts, headers, ETC... If you want performance, buy one of those, otherwise spend your spare cash on maintaining what you have and you'll have a good running jeep for a long time. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Marty, I've been a ASE Master tech for 25 years, owned my own emissions repair specialty shop for 6 years with my own chassis dyno. When the L1 test was devised, there were 1400 techs nationwide that took it 200 passed, myself being one of the original who passed. Won Colorado's Top tech award in 1997, speaker at the national clean air conference in 97'.
Big Jim probably has more real world auto repair than anyone on this board.

Don't lecture anyone about spark and ignition theory.

I've run dyno passes for manufactures of hi performance parts, oil additives and gas additives. from Superchargers to twin turbo kits. I've done dyno tuning on jeeps to roundy racer to Ice racing jeeps.

The point of all of this has nothing to do with one coil or one type of module making some small improvment.
Results can vary too greatly to know if any of the A/M parts do anything.

What it is about is one fellow asking if spending a grip of cash on a ignition system alone will pay for itself in MPG or HP? Then find out that it made no change to a good running engine and only accomplished his wallet being lighter.

Hi Po parts have a place, however, never on a stock engine.

SD

I still stand by what I recommended. I wasn't trying to be a jerk about it, call anyone a name or "lecture" anyone, either.

So Superdawg, you don't see any performance or reliability benefit to the newer Ford Factory "Duraspark 2" parts as an upgrade? All I was trying to post in response to time2play was my experience using cheap, readily available factory replacement Ford Motorcraft parts to basically upgrade the older Jeep equivalents. This mod has been around for a long time, if it's not worth a "Grip of cash" why is it still a popular mod at every jeep website except this one?

There are lots and lots of reasons.. I'll give ya just ONE!

A guy's Jeep is running badly. (all he needs is new spark plugs) He has no idea what is wrong with his Jeep. So he gets on a site and reads posts like yours..
So he does the whole enchalada.. plugs, wires, TFI..everything he has read in Marty's post..

His ride now runs like it did when new! He is a believer! So HE starts posting..How wonderful the TFI is and what all it did for his ride..Milage! Power! Smooth idle! Hell it even SOUNDS better!

The guy never knows all he had to do was spend the $20. and install new plugs..

That's how it happens.

Hey I (we) have no problem with tinkering with your engine. If a guy has fun installing a TFI or any other modification to his ride..I'm Ok with that.. As long as he KNOWS it won't do one damn thing.. other than LOOK different.
Big JIm

".... it won't do one damn thing other than look different."

BigJim, I take it that you don't agree that the new style parts won't last longer or give better service? As I said earlier, these parts have proven durability on my customer's Jeep vehicles, especially on SJ Grand Wagoneers with 5.9ls where these parts have easliy exceeded the life of the OEM parts by twice, if not more, with only plug changes needed at 30k, instead of replacing wires, cap and the rotor, too due to breakdown of the insulation and corrosion in the cap sockets.

I took it that time2play was asking about an upgrade he had heard about, not a repair for a specific problem. I'm not trying to start any flame wars here! I completely agree that one should diagnose the exact cause of a problem before attempting a repair, but as I stated earlier, if all or most of the ignition parts are due for replacement anyways, these parts work well for very little added expense. I agree with you and Superdawg that installing a race ignition on a stock engine is a total waste, and the race type coil and module probably won't last very long. These parts are factory OEM on millions of Fords, not race parts.

Jim and I have seen far worse than what Jim just described here on this and other forums as far as blanket diagnosing, leading to folks spending money they clearly shouldn't on parts they don't even know why/what they actualy do.
Some come away with a "fixed" problem....either they simply stumbled onto the fix like Jim said with the plugs, others simply say that it worked to avoid saying it did nothing and that they ended up in a shop and got it diagnosed/fixed.

Then there are the dangerous ones who will tell you that anyone can change a distributer or a timing chain or rip out all the vacuum lines and wiring on a 85 CJ7 and end up with a better running engine. Even if it were true, open forums are not the place to tell folks that they should delve into certain things, particularly without any sort of real diagnosis by a real set of professional eyes.

Example of a stupid and costly mis diag...
Post: I went in for a smog/emissions test and failed, I have a 4.0 XJ and it failed on CO.
The first most common response is O2 sensor and others chime in a say yup O2 fixed mine.
Next are the bunch who say...gotta be the cat, I put a new cat on mine and it passed.

Then the come to a forum like this one...where Jim and I say...what year is the jeep, have you checked for codes?
Then ask a series of questions like...how many miles, recent repairs or maintenance?
It often ends up with telling the poster that we recomend taking it to a shop for a proper diag/repair.

Yes, DS2 is better than points and EFI is better than carbs.
No argument.

What it comes down to is sage advice on a forum from guys who have (damn near) seen it all with experience dating back to the stone age (Jim) and guys like myself who still do it for a living everyday.

Jim and myself have had heated arguments on this board over advice and techniques and it will happen again.
Don't sweat getting pounded on a bit here, it sounds like you have plenty of skills. Just sit back and relax and put yourself in the shoes of the guys reading this who don't have any money and no trained/schooled skills to do certain repairs.. make sure they know that what you did is not always the "fix". Readers come to this forum because they are smart enough to stay away from others.

SD

"Readers come to this forum because they are smart enough to stay away from others.

SD "



I'll second that. I stumbled upon this forum about 3 years now, ever since I picked up my 99 XJ, and I have to say I was appalled at some of the ôadviceö on what would improve or repair, fill in the blank, this site is far the best place I have found to get honest advice or what actually does and does not work, from people who have actual experience. Not trying to say anyone involved in this thread doesnÆt have experience, just merely stating this site is a wealth of info. And I hope I have been able to help some with some of my posts as well. I will say I am not a factory trained tech, or even a vehicle designer, I am a Mechanical Engineer, and I have been turning wrenches, tinkering on things, and fixing most everything that was fixable and many things that werenÆt, since I figured out how to walk. Ok a slight exaggeration, but you get my point. My first question is always why, followed by howÆs that work, and I can usually figure it out, and I donÆt understand why others canÆt, but thatÆs my problem. And by stating I was an engineer I was only qualifying I do understand my limits of what I am able to do with my current education and diagnostic and repair tooling.

SD you bring up a great point, that I just realized reading your post; because itÆs not the way my mind works.
ôExample of a stupid and costly mis diag...
Post: I went in for a smog/emissions test and failed, I have a 4.0 XJ and it failed on CO.
The first most common response is O2 sensor and others chime in a say yup O2 fixed mine.
Next are the bunch who say...gotta be the cat, I put a new cat on mine and it passed.

Then the come to a forum like this one...where Jim and I say...what year is the jeep, have you checked for codes?
Then ask a series of questions like...how many miles, recent repairs or maintenance?
It often ends up with telling the poster that we recomend taking it to a shop for a proper diag/repair.ö

In my mind they guy has already checked codes and done the basic tune up, filters, plugs, cap, rotor, etc., but you are probably right, he probably would have gone straight to the shop to the keyboard, in hopes of the quick fix, willing to spend a few bucks.


Marty does make a good point too, if these parts are interchangeable, equally as functional, comparable in cost, and if they have a longer service life, in the life cycle of the vehicle maintenance costs will be reduced if parts last longer. It just has to be clearly stated what the actual benefit is. The longer service life, so money saved. Properly maintained both sound to perform equally as well. I cannot speak to this first had, I am just rewording what was said about the 2 options, with a different perspective, Life Cycle Cost. Something I deal with at work all the time, ugh.

But the key to this entire thread was what the guy asked in the first place.
ôI read somewhere that you can increase power by putting on a high output coil,like MSD,putting an adapter on top of the Distributor Cap and change some wires around.ö
This I can speak to first hand, I put the Jeggs equivalent of the MSD Blaster 2 coil on my Æ79 F150, and some Accel 8.0mm wires, they were yellow and looked cool, (my truck is yellow too) and I needed wires and plugs anyway, so I figured why not upgrade, and the coil I think was around 16 bucks and I had heard the same, more spark, wider gap, more complete burn, more power. Seemed logical to me, but I felt no performance change what so ever. And the only reason I was changing the wires was because they looked like hell, the boots had tears, and it would miss a little if I splashed through too big of a puddle, but for the most part it ran great. They only thing that was fixed with these aftermarket parts was the slight miss with the big puddle, but that would have been solved with new stock wires too.

My philosophy now is, stock vehicle, stock (fill in your favorite parts house or repair shop) parts. Personally I prefer to get the made in America part when I can find them, which usually means they cost a little more, and I prefer to get the heavier duty brakes, and the biggest battery I can fit. For the most part you have to look at the vehicle as a system that has to work together and the parts have to be properly matched to perform properly. For a completely obscure example, but one that I think everyone would understand. Would one ever connect a fire hose to house garden faucet? Obviously not, the house wont flow enough water to fill the hose.

Anyway just my 2 cents when I am stuck awake at 1:00 am. This has been an interesting read by the way.

Cheers

Sean

We haven't got into HD brake pads in a while.. Wanna go there?
Big JIm