Hei

[Dannothedude]

Went hei on the new motor any advice before putting the engine back in 1968 bronco

 

[Broncobowsher]

So much unknown here...
HEI is a GM ignition system. If you are talking actual HEI and not just lumping it into electronic ignition. So actual HEI rabbit hole...
Davis Unified Ignition (DUI) is the gold standard. Then there are the offshore clones. The clones are well known for breaking the distributor shaft and leaving you stranded.
Then there are clearance issues. Hitting the hood brace is very common. With a stock hood, expect it. Then the diameter can be an issue as well. They are big. I'll say ugly as well, but that I won't mess with. In theory, they are electrical stupid simple. But are also easy to install wrong. Hook the old coil positive wire to the batt terminal, did you remember to delete the ballast resistor? And keep the I-wire off the start solenoid since the ignition post can be sketchy on having power during start? Sometimes add a relay to really get full power to the HEI, but that is another failure point added to the system.

And we have not even got into the what cam are you running? Because the distributor driven gear has to be a compatible material for the cam. Modern roller cams need the steel gear while vintage flat tappet need the cast gear. There is also the bronze gear that works with either, but is now a wear item. Composite gears exist, don't know if they live up to the durability hype of metal gears while compatiblity of bronze. They are new and unproven to me.

But there is the HEI module run with a Duraspark distributor. Is that the HEI you want? It is simplified from what Ford did with the Duraspark module, the HEI module has 5 connections (ground + 4 wires). Run an off the shelf distributor that can be had at any parts store. All the clearances and appearances look stock. Even the module is an off the shelf part found at any parts store. No custom parts that are are special order, if even available.

 

[ntsqd]

It does add a failure mode, but I think that a relay for ignition power is necessary. GM HEI's draw a fair amount of power that I wouldn't want going thru an original ignition switch.

 

[Dannothedude]

Yes its an hei the engine has stock cam so got the cast gear it is big and ugly getting it in was a pain for sure the original hood is dinged up pretty good so thought about maybe a cool hood maybe ill return it and do the dui thank you for the info

 

[Dannothedude]

It does add a failure mode, but I think that a relay for ignition power is necessary. GM HEI's draw a fair amount of power that I wouldn't want going thru an original ignition switch.

I had read about that so most likely doing a relay thank you!

 

[ntsqd]

Depending on how comfortable you are with wiring and fabrication an option is to use a OEM Ford Dura-Spark II distributor with the HEI's module and one of the late model 'E-Core' type ignition coils. I feel that this is the best possible non-EFI ignition system. There's only a couple important points to know in building such a system.

 

[bronco italiano]

If it is the China DUI, you may be in for an unpleasant surprise.

 

[Broncobowsher]

Depending on how comfortable you are with wiring and fabrication an option is to use a OEM Ford Dura-Spark II distributor with the HEI's module and one of the late model 'E-Core' type ignition coils. I feel that this is the best possible non-EFI ignition system. There's only a couple important points to know in building such a system.

So simple. 2 wires go to the pickup coil. Switched power also shared with coil positive. The 4th wire goes to coil negative, and a tach if you have one. Only things left is to ground the module and make sure it is on a heat sink with the thermal transfer paste.

The factory Ford E-core coils are really nice. The junkyard one I put on my boat surprised me. I was accustomed to the tiny spark the boat always had. Worked. But old school industrial engines that have a compression ratio closer to a model T than a performance engine. Put that E-core on with a TFI module (triggered off points!) and you clearly hear when that fires.

 

[ntsqd]

The heat sink and the thermal grease are both crucial to the longevity of the HEI module. Any new HEI module should come with a small package of the thermal grease. Apply ALL of it! Then wipe off what squeegees out.

On the Valiant's similar system I used non-insulated spade terminals and covered them with adhesive lined heat-shrink. And then filled them with dielectric silicone grease to control corrosion at the terminals. The module's heat-sink was a piece of 2" x 2" x 1/4" thick aluminum angle that I bolted to the fender liner and drilled/tapped for the module mounting screws.

I used a Ford E-Core coil on the Ranchero and I agree, a very nice coil. The GM E-core coils are just as nice, used one on the Valiant and was impressed enough that I make no distinction between the Ford part and the GM part. Which to use only depends on what you're doing. If using a timing control HEI module then the GM coil will have a very nice plug-in harness worth grabbing and using.

 

[trailerjack]

Following this thread. I have a mid project Bronco and can either go back with ignition module (I would need to buy everything for it) or HEI. Does anyone have any links or product recommendations? I know I would need the dist and a coil.

 

[DirtDonk]

You don’t need a separate coil if you go with the GM style HEI with the large cap. The coil is integrated into the cap and comes with the unit.
No need to order it separately.

See all the recommendations in post number two and the others. No links unfortunately, but they’re pretty easy to find DUI was who started at all, and still is acknowledged as the quality part. But plenty of companies make them and it seems like the reliability is gotten better in the past few years, even for the China clones.

When you say go back, what year is your bronco? Did it already have a Dura spark? And if so, what all do you need?

 

[ntsqd]

Were I building from scratch I would go to a junk yard. You're looking for donor vehicles from the late 70's into the mid 90's, mostly for wiring sub-harnesses, but some parts too. There are two early decisions that need to be made. Ford E-core coil or GM E-core coil and 4 pin or 8 pin GM Module? This only matters because of which donors you'll need to look at for the wiring. Either coil is a good choice and IMO are better than anything available from the aftermarket (i.e. MSD, Accel, Jacobs, Mallory, etc.) even if those aftermarket parts look like OEM parts but with fancy labels on them. Either module type will work fine, one just has better connection sealing at the expense of excess wires that are of no use to most.

Parts required:
Dura-Spark II distributor
E-Core coil w/mounting bracket
GM HEI module
Appropriate wiring harness(es)
Heat-sink mount for the GM module

I strongly suggest that each OEM part be used as-is. Do not cut off the D-S II distributor's connector and replace it with something else. Instead, buy a JY harness with the mating connector and make the harness work with the unmodified distributor wiring. This way if you ever need to replace any of these unmodified components it is a simple swap and you don't need to modify a new part to be able to use it.

Ford E-Core coil looks like this: https://www.rockauto.com/en/moreinfo.php?pk=385848&cc=1106121&pt=7060&jsn=795 Note how the wiring connector is shaped. Ideally you'll use the correct connector from a donor harness for it.

GM E-Core coil looks like this: https://www.rockauto.com/en/moreinfo.php?pk=14891045&cc=1031230&pt=7060&jsn=778 Again, note the connectors, you're going to want mating connectors from a donor. If you go with the 8 pin module you're likely to find that the other end of a harness that plugs into this coil will plug into the 8 pin module.

GM 4 pin module looks like this: https://performancedistributors.com/product/4-pin-dyna-module-heidui-distributors/ There really isn't a good connector for these. Simple spade terminals will work. Unfortunately this also means that sealing those connections from corrosion is difficult. Best bet is to load up the terminals with dielectric grease.

GM 8 pin module looks like this: https://performancedistributors.com/product/8-pin-gm-dyna-module-computer-controlled-distributor/ You're going to want both of the OEM connectors although one of them won't be doing much, but having it will allow you to seal off that connection. The two exposed pins are going to want the dielectric grease trick.

I hope someone here has a listing for it, there is a cap made for the D-S II distributor that is small like the early (points) cap, but uses the 'spark-plug' terminals of the D-S II's large cap. Although some prefer it I don't think that the large cap is necessary, but that type of spark-plug wire terminal is highly desirable. The large cap's adapter can be removed as it uses the small cap's clips to hold it in place. Add a small cap rotor and it's good to go!

Use adhesive lined heat-shrink butt-splices for building the harness. Try to keep the number of terminals and splices in the two signal wires from the distributor to as few as at all possible. The signal is about 1 volt and each connection or splice is a risk. Which is to say that when you pull the harness that connects to the distributor to leave those wires as long as possible. If you've selected a good donor you may find that this harness includes the connector that you need for the Ford E-Core coil. You're going to need to put different terminals on the signal wires regardless, best if you need to shorten them rather than needing to extend them.

 

[DirtDonk]

Great write up with links! Just with the doctor ordered…

 

[Broncobowsher]

The small male cap from an IH https://classicbroncos.com/forums/threads/small-duraspark-male-cap-and-rotor.325022/
Allows the use of the Ford Motorsports plug wire set (really good plug wire set that isn't full of marketing expense)

 

[ntsqd]

If you'll forgive me for cross linking to a Mopar forum, this thread has a lot of the various details of an HEI module conversion covered: https://www.slantsix.org/forum/viewtopic.php?t=15779 It has a fair amount specific to Slant 6 engines because, well look at the forum name. Know that the OP is Daniel Stern of Stern Lighting, and he's a bit anal (maybe more than a bit) but his tech is sound & well researched. He's also found some interesting OEM parts that may be of interest, like the combo coil & module bracket with a built-in heat-sink. It was this thread that got me started on using the HEI module on my slant 6, and then on a couple IHC engines after I had converted their points dist's to a D-S II pick-up and reluctor.

 

[DirtDonk]

Funny, you mentioned slant six. I was reminiscing about my friend whose house I passed near, who had a 69 Dodge charger with a slant six.
I think his dad was the original owner. Not sure I have ever seen another charger with a six.
Even 25 years ago, it has been sitting in his driveway for a long time. Been meaning to go back over there and see how they’re doing and if the car is still there.
He was turning into one of those “I’ll get around to fixing it up one of these days”, kind of guys.

 

[trailerjack]

You don’t need a separate coil if you go with the GM style HEI with the large cap. The coil is integrated into the cap and comes with the unit.
No need to order it separately.

See all the recommendations in post number two and the others. No links unfortunately, but they’re pretty easy to find DUI was who started at all, and still is acknowledged as the quality part. But plenty of companies make them and it seems like the reliability is gotten better in the past few years, even for the China clones.

When you say go back, what year is your bronco? Did it already have a Dura spark? And if so, what all do you need?

So on my 77, the wiring was all removed and an AAW harness is going in. I have no ignition module or anything like that but do have what appears to be the duraspark distributor in there. Im thinking HEI (didnt realize it had a coil in there) would be easier since its pretty much a clean slate (I dont know the condition of the distributor per se).

 

[ntsqd]

I like the HEI modules, but am not a fan of those monstrous distributors. The large OD design of the cap came along when GM thought that they were going to run .060" spark-plug gaps. And they can, but it works all of the ignition system parts so hard that they break-down and start to fail far faster than if you run them at .045" and the difference in performance or emissions is more or less zero. So a lot of pain for no gain.

 

[trailerjack]

I like the HEI modules, but am not a fan of those monstrous distributors. The large OD design of the cap came along when GM thought that they were going to run .060" spark-plug gaps. And they can, but it works all of the ignition system parts so hard that they break-down and start to fail far faster than if you run them at .045" and the difference in performance or emissions is more or less zero. So a lot of pain for no gain.

awesome thanks, I will look for some options....the price spectrum is so wide on these, if you have any specific ones you have purchsed and had good luck with, I am all ears.

 

[ntsqd]

For the module I think the best choice is the DUI linked above in post 12. My own preference is for the 8 pin, but either will work fine.
I've used one AC-Delco HEI module and AFAIK it's still on that car somewhere in MO.