Chris Rummel's easy follow RB into Z wireing guide

[alexideways]

Thank you so mutch, you're the best, exactly what I needed at this point.

[Rumnhammer]

This is just a quicky, When you add an Autometer tach you need to use a tach adapter. For the most part you can just follow the directions, but you do need to find the main power wire to cut so the adapter can intercept the signal and give a good reading to the tach. In the case of the RB it is the main power to the coilpacks. This white wire that I have shown in this pic. you also see a good place to mount the adapter in this pic. Also in this pic you can see how I converted the linkage on the throttle to work with a cable from a Z31. The main bracket that normally goes in this place, I recycled and made basically a firewall going towards the passenger side and welded it to the bracket, then I cut the top off a second gas pedal and welded it to the small nut that goes on the end of the stock linkage rod. works perfectly.

 

[Bishopsrock]

Chris,

 

A thousand thanks.

 

I am waiting to get my car back and will follow your info for my stage 2 which is the wiring-up part.

 

I will help out with anything new that I have for the RB26DETT.

 

Superb effort mate.

 

Thanks

[Rumnhammer]

Hi again, this time I'm adding how to make the stock Z car gauge work after swaping the RB in. The RB water temp gauge sender will not send the correct signal to the stock Z car gauge.

If the stock Z car gauge works then why not keep it? After all, gauges are expensive and the way the Z has double gauges means that if you are looking to replace them, you need to find extra space, or add extra gauge pods, not to mention the extra expense of buying aftermarket gauges. My friend asked me to keep the stock gauges because he couldn't justify the extra expense of replacing gauges that work fine, with aftermarket for no reason, and didn't want to add a bunch of pods or sacrifice vents to add extra stuff. I had to agree with him, and we decieded to keep the secondary gauges stock replacing only the speedo, tach and clock.

The clock was removed and I gutted it and recycled the housing to fit the boost gauge, that way it mounts just like the clock did. No real loss since the Z car clocks rarely keep good time anyway and he will have a clock funtion on his stereo anyway. The tach was replaced and the tach adapter fitted for proper use. The other gauges were left stock. I didn't touch the amp gauge/fuel gauge combo since I didn't touch anything that conserned them. Personally I would have replaced this with a voltmeter/fuel gauge from a later model Z, but since it still worked I didn't mess with it.

The other gauge combo, the oil pressure worked, because I replaced the RB pressure sender with the stock Z car pressure sender, it goes right on, then you just reconnect the green sender wire just like stock. That just left the water temp gauge not working. To do the wiring part of this just splice in like I outlined earlier in this guide, the only problem is the RB uses a modern thermister sender and the Z gauge uses an older style sender that reads a different resistance so the RB one won't work. I did a bunch of research to see if any other Nissan senders would give the right resistance but came up empty, so that means I would need to use the stock Z sender. I got the old sender back from the guy I gave the L-28 to, only new problem is the old sender is much larger then the new one so it will not just screw in place of the RB sender. Originally I suggested you drill out and tap the location of RB sender on the intake manifold but if you look at that there is not much meat in that area and it is pretty tight as well. That option was out of the question as well because taking off the intake manifold at this point just to do that would be labor intensive.

So I looked for a solution to the problem, and found it with the Autometer in hose sender adapter. This comes as a small kit with an aluminum pipe fitting that goes into your upper radiator hose, it also comes with a brass fitting, a ground wire and 2 hose clamps.

The first thing I tried was screwing the sender directly into the hose adapter, this almost worked, but there are only a few threads in the adapter, and it is not real tight, also if you are useing a new sender it uses a retaining nut to hold the sender in place, mine is 30 years old and long since welded itself together. Using the brass adapter is the way to go but you need to use caution. The first thing you need to do is drill out the hole that goes though it so you can fit the sender in to the point where you can engage the threads on the securing nut. a 1/2inch bit will do this part, then you need to bore it out for th lower part of the sender this is done with a 9/16 bit after you do that the sender will seat into the brass adapter, the threads are real close, the Z's being metric and the adapter being SAE/NPT they are so close that it will screw in, and using some teflon tape it will work well. After you screw the sender into the modified brass adapter, you then screw that into the hose adapter. THIS IS THE PART TO USE CAUTION. Since you have bored out the brass adapter it makes the threaded section very fragile, only screw it in until it is snug, I kept going and the brass threaded section broke off in the hose adapter! That left me to extract the threads from the delicate aluminum adapter with chisels and punches, not a lot of fun!

Use teflon tape on this connection too. then you add a grounding wire to the supplyed thread and cut your upper radiator hose, removing about an inch of it and add the adapter in line. Then I used a spade connector on one end of a small piece of wire and an insulated plug connector on the end to extend and make the wire going to the sender plug and play.

Thats it! Now your stock Z car temp gauge will work just like before.

 

This first pic shows the adapter already modifed, and ready to go in, note that your brass adapter will not be as far in as this, when mine broke off it left 3 threads (really all that is needed) so I was able to clean up the theads on the adapter and use it still.

 

 

 

This pic is one shot of the adapter in place in the hose.

 

 

 

And finally this shot from the other side that better shows the wireing mod.

 

 

Chris Rummel

 

EDit I just found out from someone answering a post as to what sender to replace the RB one with, you can skip the above step if you replace your RB sender with a toyota sender part #TS198 that goes in where the RB sender is and will make your stock Z gauge work.

Chris Rummel

[Rumnhammer]

Note I edited the wiring to show powering up the VTC, I took the first test drive today, and I was really disappointed by the low speed driveabilty. The car wants to stall and is hesitant to rev up. once the engine is reved up and the boost kicks in it flys, This got me to thinking about the VTC, so I checked a second schematic and confermed that it is not connected to the eccs relay for power, I assumed it was until I checked the power to it with a test light and low and behold no power, so I went back to the schematic, and it turns out that not only does this wire which is Blue/white stripe power the VTC but also the AAC valve, and power to the 02 sensor, so that could be part of the problem, it was too late to test drive it again tonight, but I powered up the wire by vampireing into the hot when on connection near where I powered up the fuel injectors. I also edited the info earlier in this guide where you separate out the wires, and where you power it up. So if you haven't followed this guide yet you won't miss hooking this wire up.

Arent' you guys glad I'm finding all this stuff out now so you wont' feel as bad as I did, when I took the owner for a test drive today, good thing he is my best friend, because he was very understanding. I thought it was not running well and litteraly felt like crawling into a hole.

Chris Rummel

[RB26powered74zcar]

Chris, what is the exact role this brown plug plays on the rb alt.? I just wired up my RB starter and alt using the stock 74 Z harness connectors. Everything seemed to be fairly easy, except I don't know what to do with the white T plug, left over on the Z harness that plugs into the Z alt.

 

I assume the white T plug on the Z harness, for the Z alt. serves the same function as this brown plug (as shown in pic below) on the RB alt. harness? Do I need to even use it if I'm using all after market gauges (no volt meter)?

Can you give me some guidance please... joel

 

[Z U L8R]

hey chris,

my 78 280 + rb20 was cake, from the big grey skyline plug i had to make 2 wires ignition power and one constant, then i spliced in the alternator big to little and little wire to big wire, basically white/red to white/red, the oil pressure sender has 2 wires just like the 20 and the starter's self explanatory, i didn't use the rb lower harness i just changed the plugs on my 280z's and voila, the wiring was simple.....

 

now i'm on my friend's 71 240z + rb25det, #1 his wiring harness only has 1 relay, and it looks like individual ignitors on each coil pack which is why i'm assuming it only has one relay, so my problem is wiring in his white dash plug and integrating that into the ignition switch which if you can break down what wire #/color from the dash plug needs constant, ignition, start, and ground from the ignition switch/chassis that'd break it down a lot simpler for me. i'm pretty sure of myself but i'd like a second opinion. if you want me to post my thoughts first and see what you think i can do that too. the way i see the plug i wanna be like "aiight this wire needs constant 12v, these 2 get ignition power, ground this one, and this one gets the start signal"

thanks

David

 

here's another breakdown for the external voltage regulator bypass

http://www.zcarcreations.com/howto/voltreg.htm

[RB26powered74zcar]

Funny thing is, I had a post this A.M. in this thread, asking the same exact thing about hooking up the rb alt.

 

I wasn't 100% sure what to do with the T plug thats on the Z harness for the alt. I ended up splicing the brown plug off the rb lower harness onto my Z harness.

 

I had so much junk stuff I deleted from the Z engine bay (shunt, voltage reg, seatbelt interlock, etc.) which left plenty of un used plugs and connectors hanging....

 

I just hooked up the rb alt using the Z harnesses connections, and the starter the same way. I hope to get power to the starter/ alt. just like if it were the Z parts.

 

Since I'm using a Tec2 standalone ign, and all new electrical AutoMeter gauges, I should not have to much trouble getting the starter and the alt to work. The rest is all new rewire anyways. I'm soooo close to starting her up....

[Rumnhammer]

Ok, it sounds like you have a differnt series RB25 then I had. I have the first series 1. It only has the one ignitor, for the individual coil packs.

You may have a R34 series I believe these are slightly differnt and likely have a different pin out on the ecu. Basically if you know what wires you are dealing with, you should be able to hook them up similarly to what I posted in this sticky. Even though the wires may be going to different pins on the ecu then mine, if you chart them as to the function, then it doesn't matter what color they are or # they are. if that makes sense??

 

So if you match the function with the wire in the sticky it should work.

Oh, and that Z car creations alternator regulator guide was totally wrong for my application, the sensor wire on my car went nowhere, and the hot went to ground on the 75 zcar, which is why I ended up doing it my way for that step.

 

You can, primarly use the Z car lower harness, instead of splicing it into the RB, (Q did his car this way) I spliced mine in because I wanted it as plug and play as possible, and also the AAC valve wiring is on the lower RB harness as well, so you at least need to run the wires for that separatly if you use the majority Z car lower harness.

Chris Rummel

[Z U L8R]

yeah, thanks chris . i've been making headway on my friend's wiring he has a series 2 rb25det, ours with the 1 external ignitor is series one, these both have vtc, the neo motors as far as i understand came out of r34's and have a bunch of plastic crap on em, like popping the hood on one of today's newer nissans here, that's the answer i got when i was asking some jdm engine venders if they've ever came across a 25 like my friend's.

 

so far as far as the dash plug goes the only wire that's not there is the solid big red one that goes to the ignition relay because he only has an ecu relay. we're gonna cut a bigger hole through the firewall tomorow and feed the ecu harness through then get started on wiring it to the ignition switch etc. but so far since i'm not just reading, i'm doing as you're explaining, everything's running smoothly and it makes sense EXCEPT for what's making me smoke more cigarettes than usual LOL, the external voltage regulator removal.

 

the reason why is everyones' plug in the world is round except his, he's got the bastard child rectangle plug which was throwing me off and as it is this is my first external VR project. honestly, tonight is the first time i've been able to find a wiring schematic for the theory and operation of the thing so i can comprehend it and not just pray as i take his rectangle plug and wire the thing based on wire color while imagining the plug is round lol. So now i'm in the "ooOOOOo i c" process and it's making a lot more sense. This is the first place i've seen mention of the rectangle plug, check this, tell me what you think.

 

http://www.atlanticz.ca/zclub/techtips/alternatorswap/index.html

 

the only thing i'm still searching is cutting off the T shaped plug on the alternator and splicing in the rb's without mixing up the wires (i think J Soileau is seeking the same info), or checking voltage with a volt meter to determine which goes where when the car's not running in the first place lol it's only 2 wires i know someone here knows it right off hand LOL, basically the rb's plug has 2 wires, one is white/red stripe the other is blue & something i forget, and i'm searching for the answer

 

ie

 

"white/red goes to "S" and blue goes to "L" <----[that's my guess. i'll check my 280z rb20's plug/wire colors tomorrow and pray the 25 has the same colors]

 

Can anyone confirm that though?

 

Once i get that confirmation i commence "I GOT THIS! WHO'S YOUR DADDY" phase ^.-

 

all in all so far so good though chris, i really appreciate all you guys helping and so does my friend.

David

[Rumnhammer]

David, look at the posting in the sticky at the alternator wiring, the last link you posted was far superior to the Zcar creations one, notice in the 1975 wiring, it is supposed to have a green/red stripe wire? Mine didnt' have that, so I did a very basic convertion.. It really doesn't matter what shape the connector on the VR is because really you don't need to worry about most of the wires going to the VR. Going from the wires at the alternator, the white/black stripe wire that goes to the L connector on the alternator gets connected to a good "on when hot" really can be any one, I just ran one out to the engine compartment and through the hole where the green/red wire was supposed to be, the white/black wire then goes down to the alternator, where you will need to wire in a diode like I show in the pic, this is like a one way valve that keeps the engine from continuing to run after turning off the key. You will need this if you are using the RB alternator because it is 90amp.

The Yellow wire you can splice into the RB wire in my case was light green that goes to the RB S terminal on the alternator, this wire you run right to the main battery terminal. That is really all you need to know about the VR removal, I hope that clears it up a bit for you.

Chris Rummel

[Z U L8R]

thanks

 

well...on to series 2 variation number 2. the thin grey wire that goes to the 8 pin skyline plug off the maf harness doesn't have the grey wire in it to feed ignition power to the fuel injectors from there. So i'm just gonna tap into it at the injector goofy lookin 8 post plug cause it does have the wire there.

 

i pulled a green efi relay from one of my old 240sx's and i'm gonna use that for his fuel pump relay and wire that in tonight as well as bypassing the voltage regulator. then all we have to do is recirc the heater hoses, and do all the intake hose routing (he has a jun intake manifold) then we'll sit the motor in, get the fluids in, and crank it up.

 

he's running a t3/to4e which is already on, and he has some 550's but for now i left in the stock injectors so we can just make sure the thing idle's and such, he still needs to get a z32 maf and i've already wired in the safc2, but the car should still start up without a maf.

 

oh i have one more question, i've heard you wanna disable vtc after 400hp...did you already post how to wire that in though? *i'm being lazy

 

thanks for all your help.

[Rumnhammer]

You could just unplug the VTC that would be the easiest way to disable it.

Chris Rummel

[Z U L8R]

ya i saw where you wire it in to the black/white ign switch wire. i'm almost done, i did the regulator conversion last night, and i just need to swap the alt plugs and wire in the fp relay then tape it all up.

[Z U L8R]

well....with no intercooler piping, no mass air flow, no radiator, no exhaust, no 02 sensor and the fuel return line going into a gas caddy the rb25 started right up. we got more to do but at least we know the motor'll run and idle on it's own. thanks a lot Chris for your write up, it helped immensely, and all my questions got answered as i went on. thanks again cause as soon as i'm done with my friend's i can yank out my rb20 and do my 25 swap in a day or two

[AMV8(1day)]

Hey chris, I frequent this site more often but I happened to see one of your threads on this on GRM and noticed you're from Baltimore, I'm originally from the Catonsville area and am now back in MD living in the Odenton area.

Anyway, I'm getting ready to start a RB25-'77 Z swap and saw how clean and professional your friends engine bay was after you finished and was wondering if I could come by and bug you about it. I'm looking at picking up a NeoGen RB25 engine, tranny, and LSD and really want to find out what I'm getting myself into before I order the engine and find out I'm giong to need the whole front clip.

Thanks

 

 

Joseph Kacvinsky

[AMV8(1day)]

Oh and where did you get all your custom fab stuff done or did you do most of it yourself?

 

Joseph Kacvinsky

[Rumnhammer]

Hey, Joe you are more then welcome to come over and check out the RBZ, as it is still in my garage, much to my shigrin:icon_frow I would also be happy to help you out in any way possible.

 

I did all the custom fabrication myself. in my little shed.

 

email me directly or pm on here and I'll give you my address, etc.

Chris Rummel

[loy]

hey AMV8(1day) are you getting your motor locally? If so where at? The only place i've seen close is japaneseengineimport in sterling va.

[AMV8(1day)]

hey AMV8(1day) are you getting your motor locally? If so where at? The only place i've seen close is japaneseengineimport in sterling va.

Hey loy,

Sorry I didn't respond sooner but I had written out an entire detailed message about where I am most likely giong to get it and all the other places I found in my search. But apperently I didn't send it or something sense its not here, so I'll see about writing another one when I get some time at home where I have all the info. Meanwhile, I'll just say that I am talking to the guys over at JDM-online.com about a NeoGen engine, tranny, and LSD.