Lost and cornfused

[Hstrymkrs]

Greetings. I will be honest and state that I have not completed an exhaustive search, but I have completed an exhausting search and now I am the question time. Please feel free to point me to a thread that I must have missed.

As I start to reassemble this 300 I6 I am shopping for a new distributor. I was hoping to put a DUI or equivalent on it and eliminate the extraneous stuff. We are putting a 500 cfm 4bbl Summit Holley clone on it. I am almost positive that it is a non feedback carb.

I have been searching here, Full Size Bronco and FordSix as well, but I can't find a specific thread that answers my questions. They all trail off to converting to a Duraspark II. I don't feel a strong inclination to doing this. My thoughts on changing it is for improved performance. I might have missed something along the way. What is best way to change one of these ignition systems. Does anyone have any recommendations? Why do people hunt for the duraspark rather than just go aftermarket? What am I missing in more ways than one?

Thank you,

William

[Gary Lewis]

William - I like your use of the English language. Exhaustive and exhausting. Well put. It painted a very clear picture.

I don't know that there is one thread or even a combo of threads that would answer your questions, plural. So, let me try here.

You said you want "improved performance", and I think you mean as compared to an EEC system w/a feedback carb. But, just in case you meant improved performance w/an aftermarket ignition system instead of Duraspark II, let me say that I don't believe there's any performance to be had via aftermarket. At least assuming that the same timing curve is in the DS-II as the aftermarket. That's because with the reasonably easy to fire conditions in most engines in these trucks, and especially one where you've added an aftermarket carb, ignition is ignition. You see, most aftermarket carbs are going to give you a relatively rich air/fuel mix that is easy to fire, and both approaches will fire it handily.

But, back to "why not aftermarket"? And I'd say that most people want to keep a Ford ignition system under the hood. But, an HEI actually makes a lot of sense because they take one wire to power them. That's because it has the coil built into the distributor, so you feed power in and get spark out. And the only thing you need to do is to install a relay that gives it power when the key is on - and plenty of power at that because the HEI system like a lot. But, there's a downside - the HEI distributor is large, so you have to ensure there's room for it on your system.

However, a DUI, from what I've seen, doesn't have a coil in it so you now need to use the ballast resistor in the Ford harness. But, you don't need the relay as you do with the HEI. Nor do you need the DS-II box nor the DS-II harness.

So, in some ways the HEI is easier as it is a fully integrated system. But you need the relay. On the other hand, the DUI has to have an outboard coil, but that can be powered by the already-there harness.

Does that help?

[Steve83]

...300 I6 I am shopping for a new distributor. I was hoping to put a DUI or equivalent on it...

Why do people hunt for the duraspark rather than just go aftermarket? What am I missing in more ways than one?

I don't recall ever seeing a DUI for the 300/4.9, but I have to admit: I don't really look for them. My 4.9L is bone-stock with nearly a million miles, and still runs like new. I've never heard anyone get close to that from a heavily-modified engine, or one with an aftermarket distributor design.

...eliminate the extraneous stuff.

Ford didn't put "extraneous stuff" on these trucks. They have what they need to run & pass emissions when they were built.

We are putting a 500 cfm 4bbl Summit Holley clone on it.

I doubt it'll perform the way you expect, but I wish you luck.

I am almost positive that it is a non feedback carb.

Me, too!

My thoughts on changing it is for improved performance.

"Improved" is very subjective - exactly what performance do you want to improve? Reliability? Durability? Factory parts & systems (though not necessarily what the factory used when your truck was being built) are nearly always leaps & bounds ahead of aftermarket.

What is best way to change one of these ignition systems.

"Best" is very subjective; the easiest & most-cost-effective way that will actually make a noticeable improvement would be to convert to TFI-IV, but it's not a truly standalone system... It requires an EEC-IV with several functioning sensors to calculate the timing curves.

Does anyone have any recommendations?

Drop in the newest complete EFI engine with all its original emissions controls that you can find, afford, & fit in there.

[Rembrant]

However, a DUI, from what I've seen, doesn't have a coil in it so you now need to use the ballast resistor in the Ford harness. But, you don't need the relay as you do with the HEI. Nor do you need the DS-II box nor the DS-II harness.

Hey Gary, aren't DUI and HEI one in the same thing?....I mean, isn't an HEI a type of DUI? Both commonly refer to a one-wire ignition set-up, don't they? I thought that HEI was just the GM term that stuck to all of them (kinda like Stepside stuck instead of Flareside...lol).

My thoughts on changing it is for improved performance. I might have missed something along the way. What is best way to change one of these ignition systems. Does anyone have any recommendations? Why do people hunt for the duraspark rather than just go aftermarket? What am I missing in more ways than one?

The Duraspark ignition is one of those things that Ford got right. They're solid, reliable, available, etc. They're universally loved by all Ford purists...lol.

The only benefits of going aftermarket "one-wire" on a street driven truck IMHO would be ease of purchase (You can order online and it just shows up at the door ready to install), and second, for a neat and tidy appearance. The original 35-40 year old wiring and connectors can be rotten, brittle, and degrading...and some people just like to get rid of all of it, for good reason.

There wouldn't be any performance gain from an aftermarket performance ignition unless you're running over 5000 RPM on a race application. For daily driving and mild hotrodding, a stock ignition will give you all the spark you need.

Having said all that, those HEI-style distributors are a really common swap. I know when looking online at old Bullnose trucks for sale, a lot of them have those distributors. Personally, I don't like the look of them up front on a Ford (SBF) engine. They're kind of out-of-sight on the back end of the Chevy's. On a 300/6, off to the side, there's probably lots of room for them?

 

[ArdWrknTrk]

William,

To answer your question as to why people go Duraspark II. Most likely because it is very reliable and when something goes wrong parts can be found almost everywhere.

I don't know what other changes you have made to your engine that might necessitate a 'higher performance' ignition system. The Ford inline six engine is generally regarded as incredibly reliable and a torque monster.

Maybe you've installed bigger/better pistons, cam, valves, rods, headers and intake. Maybe you've done a bunch of porting and increased the compression. Maybe you expect to rev it to 6k rpm or beyond.

If you just want a one wire HEI style ignition to clean up the engine bay Skip White sells them individually or as a kit with plug wires.

Their instructions detail what Gary said about using a relay and heavy wire to connect it.

https://www.skipwhiteperformance.com/catalog/category/distributors/ford-6cyl-dist_7486/

[Gary Lewis]

However, a DUI, from what I've seen, doesn't have a coil in it so you now need to use the ballast resistor in the Ford harness. But, you don't need the relay as you do with the HEI. Nor do you need the DS-II box nor the DS-II harness.

Hey Gary, aren't DUI and HEI one in the same thing?....I mean, isn't an HEI a type of DUI? Both commonly refer to a one-wire ignition set-up, don't they? I thought that HEI was just the GM term that stuck to all of them (kinda like Stepside stuck instead of Flareside...lol).

My thoughts on changing it is for improved performance. I might have missed something along the way. What is best way to change one of these ignition systems. Does anyone have any recommendations? Why do people hunt for the duraspark rather than just go aftermarket? What am I missing in more ways than one?

The Duraspark ignition is one of those things that Ford got right. They're solid, reliable, available, etc. They're universally loved by all Ford purists...lol.

The only benefits of going aftermarket "one-wire" on a street driven truck IMHO would be ease of purchase (You can order online and it just shows up at the door ready to install), and second, for a neat and tidy appearance. The original 35-40 year old wiring and connectors can be rotten, brittle, and degrading...and some people just like to get rid of all of it, for good reason.

There wouldn't be any performance gain from an aftermarket performance ignition unless you're running over 5000 RPM on a race application. For daily driving and mild hotrodding, a stock ignition will give you all the spark you need.

Having said all that, those HEI-style distributors are a really common swap. I know when looking online at old Bullnose trucks for sale, a lot of them have those distributors. Personally, I don't like the look of them up front on a Ford (SBF) engine. They're kind of out-of-sight on the back end of the Chevy's. On a 300/6, off to the side, there's probably lots of room for them?

Well, I was WRONG! I looked up Davis Unified Ignition, which is DUI, and most of the distributors I saw were "HEI" style, meaning large and including an internal coil. However, they do make DS-II distributors, coils, ignition wires, etc. So, to be more accurate, "DUI" is a brand of ignition components, including but not limited to HEI-style distributors.

My confusion came from a discussion with Tim Meyer, who was originally going to have DUI populate a distributor housing he manufactured. This was going to include the HEI ignition module, but not the coil, in the distributor, so it was the same size as and looked like a Ford distributor. And, it required the outboard coil, like the DS system, just not the DS module.

DUI didn't get the job done in a timely fashion, and he wound up making them with someone else. He calls them Track Boss RTR, meaning Ready To Run, and says they require 3 wires: "1-hot, 1-ground, 1-negative side of coil. External ignition module not needed." In other words, you don't need to find a DS-II module, wiring harness, and distributor. Just put this dizzy in and connect it to the existing power wire, ground, and the coil.

Tim doesn't, yet, have one for the 300 six, but asked for a pic of a dizzy for the 300 and would consider making them. I've not gotten him the pic, but do y'all think there would be an interest?

[ArdWrknTrk]

William - I like your use of the English language. Exhaustive and exhausting. Well put. It painted a very clear picture.

I don't know that there is one thread or even a combo of threads that would answer your questions, plural. So, let me try here.

You said you want "improved performance", and I think you mean as compared to an EEC system w/a feedback carb. But, just in case you meant improved performance w/an aftermarket ignition system instead of Duraspark II, let me say that I don't believe there's any performance to be had via aftermarket. At least assuming that the same timing curve is in the DS-II as the aftermarket. That's because with the reasonably easy to fire conditions in most engines in these trucks, and especially one where you've added an aftermarket carb, ignition is ignition. You see, most aftermarket carbs are going to give you a relatively rich air/fuel mix that is easy to fire, and both approaches will fire it handily.

But, back to "why not aftermarket"? And I'd say that most people want to keep a Ford ignition system under the hood. But, an HEI actually makes a lot of sense because they take one wire to power them. That's because it has the coil built into the distributor, so you feed power in and get spark out. And the only thing you need to do is to install a relay that gives it power when the key is on - and plenty of power at that because the HEI system like a lot. But, there's a downside - the HEI distributor is large, so you have to ensure there's room for it on your system.

However, a DUI, from what I've seen, doesn't have a coil in it so you now need to use the ballast resistor in the Ford harness. But, you don't need the relay as you do with the HEI. Nor do you need the DS-II box nor the DS-II harness.

So, in some ways the HEI is easier as it is a fully integrated system. But you need the relay. On the other hand, the DUI has to have an outboard coil, but that can be powered by the already-there harness.

Does that help?

Gary,

While Davis does offer DSII style distributors, Davis UNIFIED Ignition describes a coil in cap 'all in one' type.

I went to their site and while they show Ford 300 I-6 options for both "race" and "street &strip" DUI, their configurator shows "no products match your search"

[Steve83]

...aren't DUI and HEI one in the same thing?....I mean, isn't an HEI a type of DUI?

No, they're not actually related. Davis has typically used HEI coils, but the concept would still work with an older (oil-filled) coil. Modern coils are substantially more-efficient, and modern ignition control modules allow more-precise control of dwell; both of which allows them to produce a higher-energy spark than could be expected from older technology, leading to the "High-Energy Ignition" distinction being created. But the TFI-IV system is an HEI, just like all other modern ignition systems. And I think a modern TFI-IV-style E-core coil can be used on older trucks without any other mods (I think I did for a little while). If used with a DS-II or DS-III, those systems would probably qualify as HEI after that mod.

...benefits of going aftermarket "one-wire" on a street driven truck IMHO would be ease of purchase...

But the DRAWBACK for a street vehicle is that it makes it TOO EASY to hotwire. And that's really the origin of the word "hotwire" - you just run 1 "hot" (12V) wire to the ignition system, and the engine will run.

...Davis UNIFIED Ignition describes a coil in cap 'all in one' type.

Coil, cap, AND ignition module inside the distributor body.

[85lebaront2]

Well, I was WRONG! I looked up Davis Unified Ignition, which is DUI, and most of the distributors I saw were "HEI" style, meaning large and including an internal coil. However, they do make DS-II distributors, coils, ignition wires, etc. So, to be more accurate, "DUI" is a brand of ignition components, including but not limited to HEI-style distributors.

My confusion came from a discussion with Tim Meyer, who was originally going to have DUI populate a distributor housing he manufactured. This was going to include the HEI ignition module, but not the coil, in the distributor, so it was the same size as and looked like a Ford distributor. And, it required the outboard coil, like the DS system, just not the DS module.

DUI didn't get the job done in a timely fashion, and he wound up making them with someone else. He calls them Track Boss RTR, meaning Ready To Run, and says they require 3 wires: "1-hot, 1-ground, 1-negative side of coil. External ignition module not needed." In other words, you don't need to find a DS-II module, wiring harness, and distributor. Just put this dizzy in and connect it to the existing power wire, ground, and the coil.

Tim doesn't, yet, have one for the 300 six, but asked for a pic of a dizzy for the 300 and would consider making them. I've not gotten him the pic, but do y'all think there would be an interest?

Gary, et al, FWIW, when the Prince of Darkness, Lord Joseph Lucas, decided to service a replacement for the OPUS system (oscillating Pick Up coil System) they released what was sold as Lucas Constant Energy system. It has what reminded me of the old Chrysler electronic ignition pickup coil with a 4 or 6 point reluctor and it was packaged with an aluminum box with a pair of connections on 90° away from each other sides. Inside the box (which served as a heat sink) was a 4 pin GM HEI module. Instructions were to mount it under the coil on MGs and discard the ballast resistor connecting the positive wire directly to the coil + terminal.

[Hstrymkrs]

Gary,

While Davis does offer DSII style distributors, Davis UNIFIED Ignition describes a coil in cap 'all in one' type.

I went to their site and while they show Ford 300 I-6 options for both "race" and "street &strip" DUI, their configurator shows "no products match your search"

This is one of the problems that I am running into. They show the distributor, but then say it doesn't fit the application.

I am fairly green at this, so forgive me if I use a general term that might need more clarification. I have been turning wrenches for many years, and I worked on generators in the military. I understand how engines work, and I can most always get them running. However, I have much to learn on the specifics and the fine tuning of the things.

By increased performance, I merely imply that I want it to run efficiently and smooth primarily, and if it gives me a little extra horses that is great. I haven't done anything to the engine other than send it off to the machine shop to have it gone through and reassembled. It is bored 0.040 over and we put a cam that claims to help increase torque/horsepower. I do not expect it to be a high RPM engine as my main goal is torque for off-road enjoyment and cruising for the joy of driving an older full size Bronco.

While I am not against the DS-II, it just seemed easier to put a DUI/HEI and move on. Whenvever I would read about them, the thread would always turn into a DS-II thread and never really go anywhere else. Most of the DUI/HEI are for the V8 and the smaller inline 6s. I was initially confused as the TFI-IV seemed to be a hybrid/transition from the carburetor to the EFI systems. I am not sure what it would take to convert to a fully EFI system, but I would think that would add cost that I can't afford. The engine is ready to go as soon as I reassemble the all the accouterments, so I am not certain that changing in mid build is a good idea for me at this moment. Additionally, I am deleting the EGR/Smog pump only because it adds extra cost to bringing this thing back up and running. My smog pump is seized up wont even make a good boat anchor.

Honestly, I am just trying to do a modest rebuild and hope to get the most out of the engine, i.e., reliability and strength.

This truck has great memories for me, and I just want to get it back up and running well without needing a second mortgage. The junk yards around here just plain suck. They want too much money for their stuff and the closest pick-n-pull is 2 hours away. If the DS-II is great and reliable then I can go that way, but the threads make is seem so complicated. I have a bad distributor and I need a new one. I don't want to cut corners, I just don't have the money to get everything now. I would honestly be happy with it being stock again. It just doesn't seem practical...not that putting any money into this old of a vehicle is practical in any way.

I appreciate all the replies and attempts to help. I will reread them and try to clarify my objectives more.

You all are a great help.

You ask what I want to do with my Bronco? Here you go!

William