Notices
1973 - 1979 F-100 & Larger F-Series Trucks Discuss the Dentsides Ford Truck
Sponsored by:
Sponsored by: Moser

HEI wiring

Thread Tools
 
Search this Thread
 
Old Feb 23, 2024 | 12:14 PM
  #1  
egchewy's Avatar
egchewy
Thread Starter
|
More Turbo
Photogenic
Liked
Loved
Community Favorite
Joined: Mar 2022
Posts: 704
Likes: 216
HEI wiring

Yes, I know it's been asked hundreds of times, but I'm going to ask again.
Also not trying to make this into a "HEI vs duraspark" debate.
HEI Batt terminal needs to see 12v at crank and run. As I understand it, there isn't an existing wire in the harness that has both.
The existing coil wire will only have 7-9v on run because of an inline resistor so that can't be used.
I've see some advocate using a 10g wire off the "I" solenoid terminal for the 12v on crank.
I've also seen other posts mentioning that I could use one of the wires going to the duraspark for the 12v on run.
I assume I could splice both of these together and plug it into my HEI?
Does It matter that I'm tapping into a smaller gauge wire if I'm splicing into the duraspark wire for my 12v on run wire?
Any problems w/ the "I" solenoid post seeing a constant 12v on run?

Bear with me...wiring is not my strong suit.
Thanks
 
Reply
Old Feb 28, 2024 | 05:51 AM
  #2  
egchewy's Avatar
egchewy
Thread Starter
|
More Turbo
Photogenic
Liked
Loved
Community Favorite
Joined: Mar 2022
Posts: 704
Likes: 216
update
after a bit of research, I think i'm going to use the power wires to the duraspark to run the HEI.
There are 2 wires that power the duraspark, one white/brown and one red. The white/brown one is 12v on run and the other is 12v on start.
Last night, I removed the starter cable from the solenoid to test those wires without cranking the engine.
I have 12.4v at the battery but no signal at the wires.
Not entirely sure if I'm fully understanding how to use the multimeter or if there truly is no power at these wires.
I have the multimeter on DC and can get a 12v reading on the battery itself. The Duraspark wires should be coming directly from the ignition switch.
I'm trying to ground my tool to a bolt on the inner fender, so maybe I have a bad ground.
I was thinking of using a voltage test light to see if it'll light up. Not sure what the problem is.
Also, my HEI is asking for 12v on crank and start. Assuming the duraspark wires are working as they should (car was starting fine before I pulled things out) I'm guessing I should be splicing the 2 wires together and attaching them to the BATT terminal on the HEI, right?

 
Reply
Old Feb 28, 2024 | 09:32 AM
  #3  
Pickupmanx2's Avatar
Pickupmanx2
Lead Driver
20 Year Member
Liked
Loved
Community Favorite
Joined: Jun 2006
Posts: 5,677
Likes: 999
From: Near Yosemite CA
I'll have to look at my 77 F250 tonight, I went HEI on it and IIRC I used one of the terminals off the DS with a spade for it...
 
Reply
Old Feb 28, 2024 | 01:21 PM
  #4  
jackietreehorn's Avatar
jackietreehorn
Cargo Master
5 Year Member
Photogenic
Photoriffic
Liked
Joined: Oct 2016
Posts: 2,738
Likes: 217
From: Northern VA
HEI should be wired to the trash can / Chevy vehicles. Kidding aside, it looks like you can use the DS modules +12V feed or original coil + to trigger new 12V relay.
 
Reply
Old Mar 4, 2024 | 06:18 AM
  #5  
egchewy's Avatar
egchewy
Thread Starter
|
More Turbo
Photogenic
Liked
Loved
Community Favorite
Joined: Mar 2022
Posts: 704
Likes: 216
OK, hopefully this helps someone else who is trying to do the same thing.
I figured out my multimeter issue. Bad ground.
I was trying to ground to the inner fender well. I assumed it would be fine to use but was wrong. When I grounded the tool directly to the block, I was able to see a full 12v on run.
I'd assume the inner fender could be grounded to...after all, the solenoid is grounded to the fender, right?
So for my HEI that requires 12v on start AND run, I'll be using both wires going to my old duraspark module and splice them together. I'll also use this for my electric choke as it runs in the same vicinity as the carb.
 
Reply
Old Sep 3, 2024 | 11:00 AM
  #6  
egchewy's Avatar
egchewy
Thread Starter
|
More Turbo
Photogenic
Liked
Loved
Community Favorite
Joined: Mar 2022
Posts: 704
Likes: 216
update.
do NOT use both duraspark white and red wires, as it'll send 12v back to the solenoid when in the run position and your starter will engage while in run.
I finally got a test light on the wires. The red wire is hot on run and start, the white one only on start.
I'm using the red wire to give 12v to my HEI as well as my electric choke.
 
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
JefflovesF250s
1961 - 1966 F-100 & Larger F-Series Trucks
11
Dec 3, 2022 12:43 PM
DirtyLarry79
1973 - 1979 F-100 & Larger F-Series Trucks
2
Mar 28, 2022 05:51 AM
ryank59701
1967 - 1972 F-100 & Larger F-Series Trucks
27
Nov 17, 2015 12:21 AM
68cabby
Ford Inline Six, 200, 250, 4.9L / 300
5
Apr 22, 2013 07:25 AM
billybodaddo
1967 - 1972 F-100 & Larger F-Series Trucks
2
Oct 25, 2012 10:44 AM




All times are GMT -5. The time now is 08:00 AM.

story-0
Top 10 Fords at 2026 Carlisle Ford Nationals

Slideshow: Top 10 Fords at 2026 Ford Nationals

By Joe Kucinski | 2026-06-09 11:10:08


VIEW MORE
story-1
3 Best / 3 Worst Parts of Modern Ford Ownership

Based on years of owning multiple modern Ford products.

By Brett Foote | 2026-06-09 10:53:36


VIEW MORE
story-2
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches

SPONSORED: From muddy boots to rain-soaked cargo, these upgrades address some of the most common frustrations Ford truck owners face every day.

By Pouria Savadkouei | 2026-06-08 18:50:34


VIEW MORE
story-3
Every 2026 Ford Engine Explained

Here's everything you need to know about every Ford engine available for the 2026 model year.

By Brett Foote | 2026-06-05 12:58:01


VIEW MORE
story-4
10 Ugly Ford Trucks That We Still Kinda Love

Slideshow: 10 ugly Ford trucks that we still kinda love.

By Joe Kucinski | 2026-06-03 09:51:16


VIEW MORE
story-5
10 Things Every Truck Owner NEEDS (2026 Edition)

Slideshow: the best gifts for dads & grads

By Michael S. Palmer | 2026-06-03 15:43:58


VIEW MORE
story-6
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath

Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.

By Verdad Gallardo | 2026-06-03 11:38:36


VIEW MORE
story-7
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer

Slideshow: 10 most expensive Ford trucks ever sold on Bring a Trailer.

By Joe Kucinski | 2026-05-27 16:24:34


VIEW MORE
story-8
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)

Here's everything that has changed for the latest model year.

By Brett Foote | 2026-05-27 16:17:28


VIEW MORE
story-9
Top 10 Ford Truck Tragedies

Slideshow: Top 10 Ford truck tragedies.

By Joe Kucinski | 2026-05-18 19:34:33


VIEW MORE