Help wiring up a DUI HEI dizzy please. (1 Viewer)

[HawkGunner]

I've been looking at wiring diagrams and reading threads here, trying to figure out how to install an ignition relay to run the HEI dizzy.

Correct me if I'm wrong please. I think I need to connect both the big and small BY wires from the plug going into the ignitor to a single post on the relay, run the wire going to the starter to another post, then a wire to the dizzy, and a wire to a body/frame ground.

A few people have posted about installing a relay, but nobody seems to have written about how exactly they went about it. I'm a wiring noob, but I'm deadset on figuring this out. Any tips or suggestions would be very much appreciated. Maybe some pictures of your setup too?

Thanks

EDIT: '78 FJ40. Original ignition setup and original 2F engine.

 

[thebigredrocker]

I just used the big BY wire direct to my HEI. I don’t think that smaller ballast bypass wire is needed. BW correct?

never needed relays for that stuff just wired them to the on side of the ignition switch

Shelfboy is right. The only thing that requires a relay is something that has a huge amp draw like the headlights etc... the starter has the relay on it (solenoid). Just wire the switch with coolermans info

Here’s some relay info

BY to Terminal 86 on relay. Ground terminal 85 to body or take it to the negative battery terminal. Connect a 12ga wire to Terminal 30 on relay then to a 15 amp fuse, then to battery +. Last connect Relay terminal 87 to the DUI. When you turn on the key the relay will energize providing the DUI with a good solid +12V.

D.U.I. Distributor

 

[Coolerman]

IF your 78 FJ40 has the Yazaki resistor wire inside the harness then you MUST use a relay.
This resistor wire took the place of the ballast resistor whose purpose was to reduce the voltage to the coil so it ran cooler.

A HEI distributor REQUIRES the FULL +12 volts and can pull a lot of amps to boot!

To determine if you have this special wire, put a meter on the large Black/Yellow wire and turn on the key. If the voltage is 9 to 10 volts, BUT reading across the battery reads 12 volts or more, then you have the resistor wire.

I have been working on a relay kit (sent one out to a person here on MUD months ago who has yet to get back to me... Hint Hint!). It will use a waterproof relay, have a built in fuse and will have the special GM connector to plug into the dizzy.

If you are interested let me know! email me as I am doing a lot of traveling this spring and don't get on MUD much. fj40coolerman at gmail dot com.

 

[HawkGunner]

I will check shortly for the Yazaki resistor.

Lets see if i have this right. If i don't have the resistor, I don't technically need a relay. If the wire is resisted, I do.

If I run the DUI through the ignition switch, sans relay, will that overload the switch eventually?

 

[WaTrout88]

Sorry coolerman, I am still working on it . . . one day I will have it done . . . and I am getting really close to jumping back on it.

 

[HawkGunner]

Ok, I have source voltage on both the big and small BY ignition wires. No Yazaki resistor... which means (I suppose) I can just run the 12ga wire straight to the dizzy and it should run. Which is great news, because my wife is tired of looking at a cruiser that doesn't run ¯\_(ツ)_/¯

I would like to get @Coolerman 's relay kit though, as it seems the ignition switch might get burned out more quickly with this setup. And it's waterproof!

As far as starting this thing up and the positioning of the dizzy, do I line up the No. 1 post with the button? Or do I turn it the 30° as stated in the manual as well?

Thanks!

 

[WaTrout88]

Sorry HawkGunner, I won't be much help here. I have not had my head into that for a few month now so I am not sure on the positioning of the dizzy. Last time I tried to fire mine up I had an engine mechanic over to help tune things in but I ran into carb issues.

 

[HawkGunner]

Sorry HawkGunner, I won't be much help here. I have not had my head into that for a few month now so I am not sure on the positioning of the dizzy. Last time I tried to fire mine up I had an engine mechanic over to help tune things in but I ran into carb issues.

My cruiser was running fine before I ran into ignition issues, and I had the carb tuned pretty good too.

Hopefully the dizzy is my last major issue until I can do a turbo diesel swap! Knock on wood haha

EDIT: I am pulling the transmission and xfer case in a few weeks to overhaul it. It leaks like a sieve, but shifts smoothly otherwise.

 

[samc2447]

I installed an HEI on my '78 when I did my fuel injection earlier this year. You will need to do what @Coolerman suggests and use a relay. I wired a relay in with 12V direct from the battery to power the dizzy, they really do need full voltage and can use some current too.

Wiring up a relay is easy and will put less strain on your stock harness.

If you want your rig to run better, ditch the Weber and get a rebuilt Aisin or buy a City Racer carb.

 

[HawkGunner]

I installed an HEI on my '78 when I did my fuel injection earlier this year. You will need to do what @Coolerman suggests and use a relay. I wired a relay in with 12V direct from the battery to power the dizzy, they really do need full voltage and can use some current too.

Wiring up a relay is easy and will put less strain on your stock harness.

If you want your rig to run better, ditch the Weber and get a rebuilt Aisin or buy a City Racer carb.

I bought a relay yesterday, just in case. I might as well go hook it up.

Everyone keeps saying ditch the Weber. Before my OE dizzy went out, it ran as well as any other carbuerated vehicle I've ever owned. Maybe there are starvation issues on steep inclines? I dunno. In any case, I'm saving up for an R2.8 swap, so changing out a carbuerater that works doesn't make much sense.

 

[samc2447]

I bought a relay yesterday, just in case. I might as well go hook it up.

Everyone keeps saying ditch the Weber. Before my OE dizzy went out, it ran as well as any other carbuerated vehicle I've ever owned. Maybe there are starvation issues on steep inclines? I dunno. In any case, I'm saving up for an R2.8 swap, so changing out a carbuerater that works doesn't make much sense.

Yeah mine had a webber on it when I got it and it started and ran ok at low rpm. I put an aftermarket carb on it and it is a night and day difference. From everything I've read, the webbers just don't allow enough airflow for these engines. Adding fuel injection made an even bigger difference in drive-ability for me.

I like the idea of a diesel swap, but I'm not putting thousands of miles on mine every month, so for me the 2F works fine. Try a carb swap and you might change your mind on the 2.8.

 

[HawkGunner]

The Holley Sniper 2barrel has piqued my interest. It's still not a 25mpg upgrade, but I'll look into it. My motor only has 60k miles on it, and the compression is still good enough for fuel injection.

But, if I had the power and efficiency of a turbo diesel... I would drive my truck thousands of miles a year hahaha

 

[Coolerman]

I also have the special HEI power connector (and the tach connector as well) for sale if you need it. Part #HEI-1 $3.25 each and includes the terminal. $6.25 to your door...

 

[Solace in Solitude]

This is the best relay wiring diagram/instructions I've found... Very intuitive... Completely self-explanatory.

Be sure to:

• use the small BY to trigger (86) the relay.
• Tape off the large BY... My '78 has the large pink Yazaki resistor, spliced into the large BY... Not needed for DUI, because your DUI requires the full battery voltage.
• Use a sufficiently sized wire for the relay output (87)... I used 10ga.
• Use a sufficiently sized wire for the battery input (30/51) and FUSE IT.
• Properly ground (85) the relay.
• 87a is NOT used... Not all relays have 87a anyway.
• Done.

12v relay wiring diagram 5 pin - Google Search:

 

[HawkGunner]

This is the best relay wiring diagram/instructions I've found... Very intuitive... Completely self-explanatory.

Be sure to:

• use the small BY to trigger (86) the relay.
• Tape off the large BY... My '78 has the large pink Yazaki resistor, spliced into the large BY... Not needed for DUI, because your DUI requires the full battery voltage.
• Use a sufficiently sized wire for the relay output (87)... I used 10ga.
• Use a sufficiently sized wire for the battery input (30/51) and FUSE IT.
• Properly ground (85) the relay.
• 87a is NOT used... Not all relays have 87a anyway.
• Done.

12v relay wiring diagram 5 pin - Google Search:

View attachment 1707437

Thanks! I spent all afternoon fixing things up with the relay and wiring.

I used the large BY wire because I don't have the resistor, but I wouldn't think it matters whether you use the primary or bypass wire to trigger the relay, even if it's resisted. Would it?

I might do a writeup for other noobs interested in this mod, with easy to follow instructions and pictures all compiled in one thread.

 

[Coolerman]

The large BY and the small BY are tied together, so electrically they are identical. You can use the small BY to trigger the relay with no issues.

 

[Solace in Solitude]

Thanks! I spent all afternoon fixing things up with the relay and wiring.

I used the large BY wire because I don't have the resistor, but I wouldn't think it matters whether you use the primary or bypass wire to trigger the relay, even if it's resisted. Would it?

I might do a writeup for other noobs interested in this mod, with easy to follow instructions and pictures all compiled in one thread.

Sorry, I'm cMped in the middle of nowhere and don't always have a signal.

I see Mark responded... yes, either BY can be used to trigger the relay.