Barefootdan's 280z Build

[Av8ferg]

Dan, if you need a hazard switch let me know. I have a couple extra in my Z hoarding box.


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[Barefootdan]

The wiring project is finally coming to a close. I’d argue that this took more work and effort than the engine rebuild and I would definitely rather rebuild an engine than another wiring harness 🙂 I envisioned that when I designed my own wiring harness digitally, it would make the whole process much faster, and in a way it did, but not how I imagined. 

What I learned by drawing out my own harness was more informational. I learned how everything worked, I became familiar with the OEM harness in both identification and functionality, and I may have gone a little crazy tracing black and white lines for hours on end. So going into this project I knew what I wanted to remove, what I wanted to replace, and what I wanted to add. I had the new diagram printed out in a 2x4ft poster for the garage and was ready to use this as my guide, but in all honesty, I probably looked at that poster 5 times in total. 

 

Once I started the actual wiring, it was far easier to do a combination of tracing OEM wires and using the OEM diagram. I still needed to find the correct length of each wire, so I needed the OEM harness with me anyways. This was also my first electrical dive into the car world, so I wanted to use the OEM diagram to ensure all circuits were correctly terminated. I think someone who is more confident in their wiring capabilities, and knows all lengths of wire (at least the minimum length needed) could use a self drafted diagram only. It just didn’t work for me.

 

Now, enough boring talk, let's dive into what I used, how I used it, and what's next! 

 

Parts used:

It was a bit of a pain sourcing electrical items with the current COVID supply chain issues. I knew I wanted to use 280 series fuse and relays for everything. I can't stand the look of regular sized relays, let alone 6 of them side-by-side. I also knew that I wanted to update all original relays and connectors to modern technology. 

Originally, I wanted to use a Bussman Distribution Block:

This was my first choice since you can neatly organize your relays on the left, fuses on the right, and choose if you want busbars integrated or not. Unfortunately it was tough to find what I wanted in stock and I knew I would need a minimum of two to fit the amount of relays and power sources I needed. So I ended up using a GEP Distribution Block:

The GEP block is similar in that it allows for 280 series terminals but allows for more flexibility in placement. The downside is there are no busbars so you will need external setups for your power in and ground.But it was available, so I can't complain! I picked up two generic busbars that had covers to hide most of the mess. It would have been so nice to just run one power wire though, via the Busmann Box.

 

I paired this with 280 series relays, the simple 4 pin relay we all know, just smaller form factor. Do note, that while this is a 4 pin relay, it occupies a 2x3 portion of the distribution block. Still, I was able to fit all relays and all circuits in this 96 pin block with room to spare. Make sure the relays you order are for 12V and not 24V and rated for the amperage you need…I may have ordered up the wrong set initially.

Next was my relay for the main power. I used an 85 amp weatherproof solenoid. Same function as the smaller ones above, just heavy duty as this is is handling all power to the car (minus the start motor):

The circuit breaker I chose is okay. It feels cheap but is rated at 120 amps and is “waterproof”. We’ll see how long this lasts but I don't mind changing this out in the near future for something closer to the 85 amps of the solenoid. For now, it works and is a nice extra layer of safety:

I was going back and forth on connectors for a while. Deutsch style, AMP style, Weatherpack style, there were so many choices and everyone has an opinion on this. Pick what you like, anything is better than 45 year old plastic at this point. I chose weatherpack because it was easy to source and the crimping tools did not cost me hundreds of dollars (I'm looking at you Deutsch….).

Funny enough, I don’t think I would recommend weatherpack if you’re doing a full harness. Or at least not only weatherpack. I used the Metri-Pack (APTIV) 280 series. And while yes it worked just fine, I didn’t like how limiting this series was. With a 6 pin connector max that was a 1x6 setup, I constantly found myself wanting 8,10,12, even 14 pin connectors to clean up the look. Luckily they do have a Metri-Pack GT 280 series that is a much more modern design with connectors up to 16 pins. There are some amazing bulkhead connectors out there as well, but it wasn’t in the budget at the time. Don’t cheap out on the terminals and seals. I bought a pack off Amazon as I was short a few, but the metal is so much worse. The knock off connectors I found to be a decent copy but with slightly worse tolerances. I used these as a last resort.

 

Lastly, the wires I used were a GXL rated wire. I picked up a pack of 18 gauge, 12 gauge, and 4 gauge for my battery leads. I would probably swap the 12 gauge for 14 gauge next time. 

 

So, we have all of the supplies, a plan, and LOTS of time to work…let's get started. I started by bringing the OEM harness to my “workshop”, aka my kitchen, and taped off connectors I knew I didn't need. Things like Air Condition, excess relays, emissions, interlock, etc. I then started with the longest wires and traced them with my new GXL wire for length. I labeled each wire to keep things documented. I only used 11 different colors and rarely had issues with micing up cables. I tried to logically use them so no two same colored wires went to a similar spot or into one connector. Once a connection was complete, I would tape the old connector as well to let me know I finished.

Doing the tracing took me a full evening for the engine side. I then tackled the dash and body. My connectors here on the OEM harness weren't bad so I decided to keep the original setup and splice my two setups together. Looking back, this worked just fine for the body harness but I wasn't a fan of doing this for the dash. The dash wiring gave me more headaches than the engine bay and body harness combined. Anyways, once my harness was laid out, I wanted to toss it in the car to see if my lengths were accurate and to give me a visual aid if I missed any wires:

Everything fit perfectly and erred on the long side which I was happy with. So I could start the terminating process! Does that make me The Terminator?! 

This took the most time and definitely was the most tedious. Each wire needs a weather seal and pin lined up in the crimper. It was also overwhelming on where to start. I have this huge mess of wires and was lost on “Do I start with the power side, or the accessory side?” I wanted to follow the flow of the current so I ended up with the power side. I mapped out my distribution block and just started one by one. It was easy to get lost in the wires but just do one circuit at a time. Each lead off the distribution block had about 10-12” of wire which would then terminate to a weatherpack connector. I would then match this with a connector at the start of my harness and connect the two once complete. I did not terminate the accessory side of the harness yet so I could trim the wire to the length needed once in the engine bay.

About 15 connectors later I am ready to start testing this spaghetti, mama mia! I immediately ran into a couple issues that I would highly recommend people do differently! First, as soon as I layed the harness in the car, I saw my absolute abundance of connectors under the dash. Was it functional, absolutely. But it was just a disaster there and I bet driving down the road would sound like a toy bin with all the connectors bouncing into each other. So I ended up ordering a pack of 12 pin connectors that would consolidate my setup. I used a 12 pin for the distribution block to the engine bay, and another from the distribution block to the dash. I do have a few weatherpacks thrown in for the body harness for my 12 gauge wires. 

The other issue I had was with my distribution block location. I knew I wanted to use the original fuse box spot, but when I did my wiring, I didn’t have exact lengths for everything (Block to busbars, block to harness, etc). I would suggest people tackling this to make their mounting plate first, then start your terminating. I had to shorten everything after I made my plate, oops!

Once we settled that, I could start running my main power. I ran 4 gauge wire from my battery to a 125 amp breaker. From there, we travel to the 85 amp solenoid. This is triggered by a master kill switch on my switch panel that always sees 12V (through a fuse). This will finally feed power to my distribution block.

I didn’t want to hack up the original mounting plates so I used existing holes and I am satisfied with how it came out. I would prefer the breaker to be hidden but I can always move it in the future. 

So I have power now and the testing can begin. I started with simple circuits like my fan relay, starter relay, etc. I created a spreadsheet that lists all circuits and if they were functional yet. In my previous posts, you will see that I ran into a couple hiccups along the way but nothing major. I can't tell you how many times I wasted 20 minutes or so diagnosing a circuit when either the main harness wasn't even connected or my power switch was off! Too many things going on in my head and I lost track of what was done. I mean c'mon, this looks organized right?

…right?!

What a mess!! It looks worse now than when we started. But I promise it works! And I promise not to shove it up under the dash as is 😄 There are a few items left to still test, but I cant before the engine is hooked up to the new carburetors. Things like oil pressure, alternator, tachometer, etc. I feel confident enough now to start looming my harness and wow what a difference this makes.

The harness now comes back out again to get a last review to make sure all of my splices are sealed and nothing is mangled up. In my spreadsheet, I updated all of my notes to match what color wire I used, where it is pinned, and when it sees power. This changed a couple times during my testing so I am glad I did this step last.

 I used this split loom in various sizes to wrap. It was very nice to use and allowed for T-offs very easily. This was also nice to use since I didn’t need to remove my connectors to wrap. 

Each end was also taped up with some fabric tape just to ensure nothing would shift around or unravel. I grabbed a firewall boot to help keep the elements out as well. Here is the final product, a fresh harness! I am so pleased with how this turned out.

 I hope this helps you guys with any wiring projects you run into. Feel free to ask questions about specifics like what pins I used, what tools, quantities, prices, etc. But this post is already mega long so I spared you the details 🙂

 

But now what? The carburetors are getting dismantled for the ultrasonic cleaner, and rebuild kits are ordered up. Once every circuit is finalized I will move my way to the interior, finally!

 

[ETI4K]

I haven't read through your entire post yet, but what I have is most impressive.

This is particularly exciting for me as I am planning the very same course of action.  The detail and commentary you've provided will be most helpful.

Very nicely done, sir.

[ETI4K]

Any chance you'd be willing to share your spreadsheet?

I started one last year for wire sizing, overcurrent device, fuse block ID, etc.  I had to stop work on it to get some other long-lead tasks moving.  Sounds like seeing yours would be very helpful for several reasons, but especially since it's been implemented and cross-checked.

[Barefootdan]

Absolutely @ETI4K! I will say that it is very basic and has many OEM circuits removed for simplicity. But I will definitely clean it up and share it here. 

[Av8ferg]

Wow, you’ve be busy. Very impressive.


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[ETI4K]

19 hours ago, Barefootdan said:

 many OEM circuits removed for simplicity.

Yeah, me too.  Actually, lots of circuits that are being labeled "NBU" - Not Being Used (same with a bunch of parts) and will be stripped out of the existing harnesses.  Several, ok, many, new circuits to be added as well.  So much so that I'm in the throes of a dilemma - should I modify old harnesses or just make completely new ones?  The more I think about it, the more clear becomes the answer - NEW!

[Barefootdan]

Here you go @ETI4K! Each table is its own connector. I copied and pasted from my excel doc so hopefully theres no major formatting issues. A few of the colors didnt translate well but highlighting the cell makes it readable. I didnt mark what was removed though, although I'm sure its fairly easy to see 🙂 I did notice one connector where the colors of two cables look to be swapped (highlighted red) so I will double check that circuit. Lastly, I fused based on a quick google search, but I may be off in some cases. So far nothing is under fused as I havent had any pop.

 

ECU 12 Pin

ECU 12 Pin

Checklist

Working?

PIN

ECU SIDE

ENGINE SIDE

FUNCTION

PIN

ECU SIDE

DASH SIDE

FUNCTION

Main power

Yes

1

Green

Orange

Horn

1

Red

Pink

Switch Panel Power

Starter

Yes

2

Yellow

Purple

Reverse light power

2

Brown

Brown

Ignition Switch

Fans

Yes

3

Blue

Blue

Inspection light

3

White

White

Fuel Pump Switch

Fuel Pump

Yes

4

4

Blue

Blue

Fan Switch

Ignition

5

Black

Red

Headlight negative

5

Light Green

Light Green

Low Beam Switch

Low Beam

Yes

6

Blue

Blue

Fan power

6

Blue Red

Blue Red

High Beam Switch

High Beam

Yes

7

Black/Blue

Black/White

Ignition

7

Blue White

Blue White

Cigarette Lighter/Map Lamp/Brake Switch

Map Lamp

Yes

8

Grey

Grey

Starter Solenoid

8

Green

Green Black

Horn

Brake Lights

Yes

9

Orange

Pink

High beam

9

Grey

Grey

Starter Switch

Horn

Yes

10

Brown

Brown

Headlight R

10

Blue

Blue

Water Oil Gauge

Gauges

Lights work

11

Light green

Grey

Headlight L

11

Red

Green

Turn signal switch power

Reverse Light

Yes

12

12

Green

Green/Blue

Running light switch power

Parking Lights

Yes

Oil Pressure

Tachometer

Misc Connectors

Gas Gauge

2 pin - Dash

Engine

Turn Signals

Yes

Pink

White

Main power

Hazards

N/A

Purple

Black

Main relay

Inspection Light

12V

Radio

N/A

2 Pin - Dash

Engine

Alternator

Need internal regulator

Yellow White

Purple

Thermostat Temp

Green

Green

Temp Relay Power

1 Pin - Fuse Box

Engine

Black

Black

Ground

Top

Bottom

Fuse Box

3 Pin - Body

Dash

Starter relay

10 amp

High Beam Power

7.5 amp

Switch panel

7.5 amp

Green Red

Green Red

Turn Signal LH

Gauge power

7.5 amp

Cig lighter

10amp

Green Black

Green Black

Turn Signal RH

Fuel pump relay

15 amp

Headlight Relay

7.5 amp

Water gauge

5 amp

Green Tellow

Green Yellow

Park Brake Light

Reverse light

5 amp

Fan relay

20 amp

Ignition relay

10 amp

Hazard

5 amp

4 Pin - Dash

Engine

Running light switch

10 amp

Blue

Light Blue

Tach Signal

Horn relay

5 amp

Inspection light

3 amp

Yellow Black

Yellow

Oil Pressure

Turn signal switch

7.5 amp

Green Black

Blue

Turn Signal RH

Green Red

Yellow

Turn Signal LH

4 Pin - Dash

Body

Red Blue

Red Blue

Dimmer

Yellow

Yellow

Gas Gauge

Black Yellow

Black Yellow

Brake Switch

Green White

Green White

Running lights

4 Pin - Fuse Box

Engine

Green Yellow

Red

Brake Switch

Black Red

Pink

Reverse light

XXX 12V Signal XXX

Grey

Alternator lamp

Green White

Orange

Running lights

3 Pin - Fuse Box

Body

Blue

Blue

Hazard Power

White

Green

Fuel Pump Power

Black

White Black

Fuel Pump Ground

4 Pin - Dash

Fuse Box

Red White

Light Green

Headlight switch power

Red Black

Orange

High Beam

Black Blue

Green

Low beam

Green

Blue

Gauge power

 

edit: mobile site does not work well with this table! 😂 use your desktop if you want any readability 

Edited February 17, 2022 by Barefootdan

[ETI4K]

It all seems to have come through successfully.  I just did a C&P into Excel and it all looks good.

Thank you very much for sharing it!

[Barefootdan]

Now that the wiring is done, I was able to start working on cleaning up the Mikuni's. I purchased an ultrasonic cleaner large enough to fit the main body of the Mikuni and started to disassemble. They were pretty nasty and one even had some old gas that smelled horrible! I didn't take too many photos but here are a few:

The first carb going in! I had enough room for cleaning almost an entirely disassembled carb in one shot with the 10 liter size. I used Simple Green Purple HD (safe on metals) mixed 1:3 to water. I set the temperature to 75 Celsius and ran it at 20 minute intervals. 

 

They came out great. Now perfect or new by any means, but for a "set and forget" clean, zero scrubbing, I'm very happy!

 

If anyone is familiar with the PHH carbs, there is a check ball in the accelerator pump assembly that can get seized. 2 of my 3 were not moving when I started cleaning. They took almost a total of 2 hours of cleaning in the ultrasonic machine before they broke free. But it worked! I was worried as these are no longer in production.

While I was cleaning, I finalized my velocity stack design and set my printer to work. I love how my first came out! This is ASA material which can withstand about 100C before deformation. It'll be interesting to see if the header wrap and heat shield is enough mitigation or not.

The first mock up:

 

But then I found a set of aluminum stacks for dirt cheap and I couldnt resist!! They look so good and I am glad I bought these. I still want to toy with the printed stacks as they are a more ideal length (100mm vs 55mm). Maybe once I find the perfect design via printing, I will order a machined set.

I want to find angled banjo bolts. I dont like how I have to run excess line to prevent rubbing on my throttle linkage. These will work for initial tuning at least. 

 

Lastly, I was bored and printed a new knob for my Bluetooth receiver for the car. I modeled it after the side Z badging:

 

I cant wait to hear these run but first I need to get my interior back in. The carpet has arrived and I am letting it air out in prep for the install. 

 

Lastly, I have one question for the wiring guru's. My ballast resistor is confusing to me. There is a Black/Blue wire that see signal only during cranking:

Why is this? 

I did not notice this getting power only during cranking and supplied 12V during my test. The ballast became very hot after a a few moments (obviously because I wired wrong!) and I was not seeing spark. Disconnecting this wire gave me spark consistently. 

EDIT: I found out why it is getting so hot. I ran it to GROUND not 12V power. So now that makes sense at least. But I am still confused as why this sees 12V only during cranking and if it is still needed. Thanks all

 

Edited February 28, 2022 by Barefootdan

[Barefootdan]

The Datsun runs once again! Still need to dial in my ignition timing, jetting, and fuel lines. But here is a sneak peak. I called Dave over at tuning4performance and had a nice chat about these mikunis. Ordered up a few sets of jets as I am running rich right now by the look of my plugs. A wideband O2 will be a nice addition in the future for fine tuning. 
 

 

[Barefootdan]

Got my jets from Dave and wow it’s already responding way better! I’ll have to wait a little longer before a street test but I’m super excited. 
 

In the mean time I have been putting the interior back in as I get the pieces. Carpet is done minus the inner scuff plates. 
 

I finally got around to completing my switch plate and radio housing. I used a laser cutting service to get some plates printed. I played around with some materials and loving the Brass. Kinda old school mixed with new. Shines nicely with the sunlight. 

 

Flipping my BAT switch to show the start light and volt meter. 
 

 

The Z knob on the right is my Bluetooth radio. I’m glad with how it all came out. I have multiple cuts of the plates so I’ll toy around with trying to get a texture finish for the black to blend in better. I’m thinking wrinkle coat maybe?