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1978 Bronco XLT Ranger
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21 Posts
Discussion Starter #1
So first off, I'm sure there will be opinions on whether or not to install an HEI on a Ford motor and I appreciate everyone has their preference, but I have decided this is the way I want to go and already have the HEI ready to go in.

My questions are, do my plug wires go in the same order as they were on the stock distributor and what is the best way to get the 12vdc needed to run the HEI?
I appreciate any info y'all can share as I have done research, but I suffer from lack of confidence in myself when it comes to certain things and I want to be 100% sure I'm doing this right without damaging anything in the process.
 

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Addicted to Junk
85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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11,475 Posts
What HEI are you using?

Yes, plug wires go in the same spot and order. Well, the same spot isnt even that important, as long as the rotor points at #1 plug wire when the engine is at TDC on the #1 cylinder. Same order is important.

First I'll describe the HEI setup on my 300-i6. I'm running the Davis Unified Ignition HEI. It is what's called a one-wire dizzy (plus a tach signal wire). That wire is fed from a 300amp solenoid/relay. The relay is fed straight from the battery. To turn the solenoid/relay on, I use a toggle switch on the dash. So to start my bronco, I flip the switch to turn on my gauges (another story), flip the switch to turn on the new, secondary ignition solenoid/relay, then turn the key. To stop the engine, I must use that toggle switch to kill the ignition. Turning the key off does nothing but lock the steering wheel.

The instructions will tell you to turn on the secondary solenoid using the ignition wire from the key cylinder. I couldn't find one that was hot in both run and start position. Hence my toggle switch wiring. Mine is not a DD so it's not a big deal.

I read a thread last night about a guy with a 400 running a distributorless ignition from a late model 5.0 explorer, so anything can be done.
 

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1978 Bronco XLT Ranger
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21 Posts
Discussion Starter #3
I am going to use an HEI built specifically for Fords from JEGS. Unfortunately the instructions are terrible and don't really pertain to a 78 Bronco. I am looking for a wire that is hot in start & run, then I will use that 9-10VDC to fire a relay that has 12VDC straight from the battery.
(I've been reading all night) I just don't know if there is a place/wire that does what I want it to do?
 

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Addicted to Junk
85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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11,475 Posts
That was the issue in my 85. I was in a rush to get it to Moab, so I gave up and wired in the toggle switch.

Not sure if @schwim or @miesk5 can help locate that wore or not?

My rig was a feedback EECIV carb. The PO converted it back to a points style, with a pertronix ignitor kit. So my wiring was really hacked up.
 

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I'll look under the hood in the morning to see which wire I found that fits the bill.
 

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78 Custom 351M NP435 NP205 Sniper EFI Hedman Headers Magnaflow Muffler 4.56 Gears Grizzly lockers
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1,352 Posts
I'm assuming that would be the same wire I used on my Holley Sniper. On the 78/79's there should be a wire on the firewall near the giant A/C box (if you have that monstrosity) that stays hot during cranking. Before I put on the EFI it was hooked up to my Edlebrock carb's electric choke. My 77 F100 has the same wire, but it is unused as it came with a stove-choke from the factory.

I'm going through my mess of pics on imgur to find anything that may help show what I'm talking about.


Edit: adding pics.


Here's the hot mess that is my Bronco. The wire that was on my carb's electric choke is in the bottom left of the first pic. You can see the connector touching the wire loom.

Second pic shows that connector cut off and spliced to my EFI harness wire (pink wire to green wire). If you follow the wire you'll see the factory plug that it connects to.

Third pic is of my F100 and it shows the factory plug you can tap into (same one I used on my Bronco) if it's not already wired up to anything. I cut a matching connector out of another truck so I could plug into it with a more factory look rather then cutting the factory plug off and crimping wires together.







 

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Addicted to Junk
85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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11,475 Posts
I never considered the electric choke wire for mine... I swear I probed every wire on the column twice and none were hot in both run and start
 

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78 Custom 351M NP435 NP205 Sniper EFI Hedman Headers Magnaflow Muffler 4.56 Gears Grizzly lockers
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1,352 Posts
I never considered the electric choke wire for mine... I swear I probed every wire on the column twice and none were hot in both run and start
I'm pretty sure from all the probing with my test light that it was the only wire under my hood that was hot in the run position and during cranking. I knew it was available before I got my Sniper, because of my F100. I used it as a source for some DRLs on that truck, so the lights (when that plug is connected in my third pic) come on as soon as the key is in the run position.
 

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1978 Bronco XLT Ranger
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21 Posts
Discussion Starter #9
Thanks for the pics Doosenberry

So I got the HEI all wired up and I verified that I have 12.8 DC at the HEI when the key is on.
Got the truck to start up first crank but it is running terrible! It runs and idles but it chugs like a train, just sounds awful.
I messed with the timing a bit and it changes a little but still chugs. I metered the incoming voltage to the HEI while running and it is 15.1 vdc
I feel like I'm missing something, but I have checked everything that I can think of...
 
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