'74 260Z: relays, fuel lines and emissions, oh my.

[jun]

I just took delivery of my latest project- a well loved '74 260Z!

As I get to know this car and all of its quirks, it's becoming more and more apparent that some serious organizing and deleting is in order.

 

My vision for this car is a no nonsense, minimal car in regards to creature comforts. All of the accessories on this car are being deleted. rear glass defogger, heater, AC (it used to have AC) etc. can all go. I noticed a huge bank of relays in the engine bay, and a rats nest of wiring that I'll have to go through.

 

I also noticed some peculiar fuel lines and other details that are/were emissions related. Of note is that this car has already been modded with round top SU's along with a host of other mods, some good, some not so good.

 

With that said, I am reaching out to you guys for a little guidance here. I've combed the web looking for wiring diagrams, previous experiences, etc etc searching for answers. I've found a few, but wondered if any of you could shed light on what I'm looking at here. Have a look at the pics below, I welcome any information you can provide!

 

First, a shot of the engine bay as it is now. Lots of work up ahead. You'll see some notes. The fuel line looks like it does a U-turn at where I marked (1) near the valve cover. Then it appears to go back down (2) where it came from- is this going back to the tank? If so, can it be simplified and deleted?

 

 

 

And now, that relay collection. I'm assuming not all of these are needed to run the car- I suspect some of this can be AC/defogger/etc stuff. Anyone know what relays are what? I've labeled each one with a number, and they all correspond to the same relay, no matter which image. I'd be happy if someone could chime in here. Relay #3 appears to be a replacement, but I am not sure what it replaced. #2 was missing a cover and was wrapped with plastic wrap :lol:

 

 

Moving on to the coil. I assume (1) should be plugged in somewhere. I also wonder if (1) and (2) can go away if I replace the coil with a MSD?

 

 

And what I assume were ports for emissions at some point, there are some open areas, and some fancy tube work on the balance pipe. Can all of the circled areas be blocked off?

 

 

The car runs good, it needs some new gaskets (including a HG) so I'll be going through all that as time allows. Right now, I need to get rid of any excess, and make sense of the wiring and plumbing so I can get a better picture of what I need to do. Eventually I'd like to get it cleaned up and simple so it's on course with my 510 engine bay.

 

 

In any case, I'm excited at what lies ahead with my Z! Any info you guys have is appreciated greatly.

[banzai510(hainz)]

Jun

I assume you still have points?

as a 74 should have points and a ballast resisitor

#1 I always get rid of and never notice a difference But I cont vert to Pertronix ignitions.

#2 is the Ballast resisitor and HOT start wire set up.

If running points youll need this whole set up.

 

When You say MSD you mean coil or you mean coil and the MSD box? If you going to put sa MSD coil only I say DONT do that.as its a lowr ohm valve and cause more current thru the points thus arching and burning up sooner.

 

If you going to use the WHOLE MSD set up I guess go by the instructions from MSD as I believe the point are just used a sa trigger and dont need to worry about the CURRENT as the box takes care of that But I really dont know about MSD set ups.Im winging it!!!!!!!!

 

Or get a matchbox for a Z car and use a MSD coil is fine. Hook up the ON wire and START wire right at the +side coil /B of the matchbox

C goes to - coil thats it

[datzenmike]

On the smog items. You may be exempt but it still has to pass a visual and everything has to at least be there.

 

You check that it's an L26? Look on block below head behind the dip stick? Could be an L24 swap because the carbs are earlier dome top not 260z flattops. EGR was introduced in '72 and there's no EGR on it, so early L24 manifold at least.

[jun]

Hainz, good point. It's been so long since I installed the matchbox in my 510, I forgot to check the distributor to see if it has points or not.

I guess I should start looking for a Z matchbox. I did find some information on the swap, and it looks like that alone will eliminate a lot of wiring and junk.

 

Mike, that is also a good point. Let me check what engine is in there, hah!

I bought the car from a very good friend of mine, and he said it's been through quite a few owners. As challenging as it can be to go through some of the ill-planned mods of previous owners, it is fun at the same time. It's always worth a good laugh.

[datzenmike]

There were two modules used. Make sure you get it or swap it to an E12 80 . The other kind are E12 93 and have a second set of terminals on the lower right side. I think it's some kind of ignition retard tied to the EFI. It won't work on a carb motor.. the E12 80 will.

 

 

.

[jun]

Thanks Mike. I'm in touch with someone who has the dist with correct module for sale.

[Ratty260z]

xenons30.com will have any wiring diagrams you could ever need plus anything else you need to know in their manuals. You can get a fuel rail from Pallnet on hybridz if he is still making them for pretty cheap I believe he has a website as well.

 

Most of the wiring can be cleaned up, upgrading to a 280zx alternator will eliminate the small box with 2 wire fuses on it and you're external regulator (big box under the fusible links), looks like you already have some round top SU's so thats a plus :D Some of the relays in the box are for the electric fuel pump back by the tank, You can get rid of the condenser under the coil with the E12-80 dizzy swap, Hybridz will have good info on what you can delete. All the ports on the balance tube can be eliminated, you could even move the brake booster port to the end of the balance tube for a cleaner look.

 

This is a picture of my Early 260z engine bay before I sold it, 280zx alt, E12-80 dizzy, 3 screw round Tops, some wiring delete, etc.

 

 

[jun]

Ratty, thanks for the great info!

regarding this line from your post: "upgrading to a 280zx alternator will eliminate the small box with 2 wire fuses on it and you're external regulator (big box under the fusible links)"

are you referring to #1(ext regulator) and 2 (fusible links) in this image? Those boxes are ugly, I'd be happy to see them gone!!!

 

[datsunaholic]

The fuel line U-turn is for the return side. The point is to keep fuel flowing in the lines even when the carbs aren't needing it. Prevents vapor-lock. It's a good thing to have, even if it's ugly. It also extends fuel pump life, since the free flow reduces the pump trying to work with no flow.

[jun]

Ratty, I got the link the FSM to this car, which is the kind of info I needed to locate what is what...thanks buddy!

Datsunaholic, I hear you on the fuel return. It will stay. :)

[Tristin]

Jun, I dont know shit about Zs, but Im excited you have a new project. I eagerly wait updates :)

[jun]

Jun, I dont know shit about Zs, but Im excited you have a new project. I eagerly wait updates :)

 

Updates will be slow, there won't be a build thread for this one. I'm just going about it as time allows. I do have some plans for it, but it will be a while before any of them are realized! As you saw, I was originally looking for a 1st gen Celica but they are not common around my parts. But then this Z came up and since it's a friend's car, I felt like it was the right project.

 

Well, some further research on other forums and the FSM, I've discovered what those ugly boxes are. They are part of the interlock system which was some sort of government mandated safety feature. Whatever it is, it needs to be deleted! The box with the missing cover is a fusible link. And the really big box is a "shunt" and its sole purpose seems to be only to run the ammeter, which I'd like to replace with a voltmeter. The random newer relay doesn't seem to be plugged into anything important, but I suspect it was for the monster stereo system my friend yanked out.

 

I need to do a bit more research before I start going at the wire harness. After the wire tuck job on my 510, I really don't want to do that again for a while. Maybe I'll just clean things up and leave it alone for now, and focus on more fun things, like deep barrels and suspension. :)

 

If anyone has any experience with disabling and successfully removing the interlock system on the 260Z, I'm all ears. Ratty260Z, did you delete this system from your car? From the looks of your engine bay, it appears that you did.

[Ratty260z]

I'll see if I can dig up some links on what I did to remove the wiring, I did do the Voltmeter swap and removed the shunt, etc.

 

http://atlanticz.ca/zclub/techtips/electrical.htm

 

This will have a majority of the wiring deletes/upgrades the main part of the tech tips has some good stuff too.

[jun]

Thanks Ratty, any more links would be helpful! I've found a few on hybridZ, but they don't seem to end with successful results. For example:

http://forums.hybridz.org/index.php/topic/28792-74-260z-wiring/page__st__20__p__808877__hl__%2Binterlock+%2Bbypass__fromsearch__1?do=findComment&comment=808877

 

I did find the thread about the alt swap though:

http://forums.hybridz.org/index.php/topic/104933-1974-260z-with-e12-80-280zx-distributor-swap-wiring-with-tach-hook-up/

 

After removing all of the relays last night and having a good look at them, I've made some discoveries. #4 in my photo is the actual emergency switch mounted on 260's, but the button is broken off. It's also bypassed as 2 wires are cut and twisted together, which I found out is a TSB issued by the dealer to bypass the interlock.

 

Bypassing it is all good, but I want to remove the system completely.

 

I also suspect the newer relay (#3) could be a replacement for one of the fuel pump relays.

 

It definitely appears that the 260 has a lot more wiring and junk than it needs. I look forward to getting rid of this stuff, but only when I can find the right information to make sure it all works out. It seems like there are a few non running 260z's as a result of unsuccessful interlock system deletes.