1995 LT1-T56 to 1975 280Z paper

[Guest 73LT1Z]

I've been working on this as time allows, and have come up with a MS Word 2000 document to assist me (and anyone else) with adapting a 1995 LT1/T56 into a 1975 280.

 

Here is the link to the doc on my website (I D/L'd it tonight & it worked OK). It is about 700K, so I did not attach it here.

 

MS-Word Doc (edited 10-22-06, about 700K)

 

This is still a work in progress (the Z only has 2 wheels on the ground ), so I'd appreciate the collective expertise here to review it & see if I've missed anything. After you read/edit it the first 200 times, it all kind of runs together. Also, it started out as being for a '73 240, so I have made a few changes along the way.

 

I have the wiring diagrams from the Haynes manual for the Z as a JPG, but there are too many from the '95 shop manual to try & scan.

 

Edit:

Links to BIG 280Z wiring diagrams (2900x2400, about 900K each) :

Wiring Diagram 1

Wiring Diagram 2

 

Connector plug wiring diagram (handy, but the wire marked as voltmeter is the alternator lead that needs the resistor and then connected to switched +12V, or just wire it as the diagram shows)

 

NEW (12-06) wiring diagram (2.2MB BMP file)

 

Note that some of the yellow wires don't show up real well.

 

Document & diagram updated 12-06. Still finding out some things don't fit as planned, so I'll keep on editing as I go!

 

EDIT

These links will go away soon due to a move to a non-Comcast area. I have revised the diagram to include a sense wire with a 470 ohm resistor inline that is connected to a +12V ignition on source, or to an idiot light (the resistor imitates the light's resistance). I failed to do this on my conversion and damaged the alternator.

[wheelman]

I read through most of your document and found only a couple things.

First I need to state that I installed my LT1 into a 73 240Z, it came from a Caprice cop car and I used a T5 rather than the T56. Because of this some things were different for me.

 

1. I wired my starter exactly as you stated using the Datsun positive from the battery and the solenoid lead from the ignition. It works but the VATS must be disabled otherwise the engine runs for only a few seconds.

 

2. I reprogrammed the PCM to remove the VATS requirement rather than jumper the pins, this also works but requires a programming cable and software or send off the PCM.

 

3. I'm using a 280Z tach and connected the tach output lead from the PCM directly to the sense wire on the tach. Once the ground was connected it worked fine and I recalibrated it using the JTR method and a data logging program to get the actual RPM.

 

4. I would seriously consider installing larger fuel feed and return lines. The LT1 will consume more fuel than the L28 and at high RPMS might be starved and run lean. I know some guys run the stock lines but I think it's asking for problems. This is much more of an issue in a 240 or 260 than a 280.

 

5. The LT1 PCM really wants a VSS and if you use the JTR tail section it eliminates it. I would stick with the stock VSS and either use an electronic speedo (there are several that work) or get a speedo drive box for the stock speedo. I tried to run mine without a VSS and it did OK unless you shifted down and used the tranny to slow the car, then it would die almost everytime. There is a discussion about this in the JTR EFI book. I used a 4 pulse per/rotation signal generator inline with my speedo cable as a VSS and it works fine. If you want the part # and vendor I can find them. It doesn't produce 4000 pulses per mile because it's driven by the speedo output rather than the driveshaft. I think the T56 is 17 pulses per rotation and the 4L60E is 40 pulses per rotation of the driveshaft.

 

6. I grabbed the underhood fusebox from the donor car which contains the fuses for the injectors, fuel pump, fan(s) and PCM power circuits along with the required relays. This made hooking up those items very easy.

 

Hope this helps. If you want more specific info about how I wired things let me know and I'll see what I can do.

 

Wheelman

[Guest 73LT1Z]

Thanks for the info, I've added comments below-

 

I read through most of your document and found only a couple things.

First I need to state that I installed my LT1 into a 73 240Z' date=' it came from a Caprice cop car and I used a T5 rather than the T56. Because of this some things were different for me.

 

1. I wired my starter exactly as you stated using the Datsun positive from the battery and the solenoid lead from the ignition. It works but the VATS must be disabled otherwise the engine runs for only a few seconds.

 

[b']I think this was due to fuel cut off, as the VATS (PASS-Key II) disables the starter & the fuel supply. My workaround is somewhat complex & expensive by using the Theft Deterrent Module ($115 or so), but the PCM needs a 50 Hz / 5V signal & I'm not skilled enough to know how to build something like that.[/b]

 

2. I reprogrammed the PCM to remove the VATS requirement rather than jumper the pins, this also works but requires a programming cable and software or send off the PCM.

 

I'm planning on buying LT1 Edit, and already have the cable from my Trans Am.

 

3. I'm using a 280Z tach and connected the tach output lead from the PCM directly to the sense wire on the tach. Once the ground was connected it worked fine and I recalibrated it using the JTR method and a data logging program to get the actual RPM.

 

This is great news- I had no idea if it would work like that, but I'm glad to see that it does.

 

4. I would seriously consider installing larger fuel feed and return lines. The LT1 will consume more fuel than the L28 and at high RPMS might be starved and run lean. I know some guys run the stock lines but I think it's asking for problems. This is much more of an issue in a 240 or 260 than a 280.

 

A good point. I plan on editing the paper to include this and a better aftermarket fuel pump.

 

5. The LT1 PCM really wants a VSS and if you use the JTR tail section it eliminates it. I would stick with the stock VSS and either use an electronic speedo (there are several that work) or get a speedo drive box for the stock speedo. I tried to run mine without a VSS and it did OK unless you shifted down and used the tranny to slow the car, then it would die almost everytime. There is a discussion about this in the JTR EFI book. I used a 4 pulse per/rotation signal generator inline with my speedo cable as a VSS and it works fine. If you want the part # and vendor I can find them. It doesn't produce 4000 pulses per mile because it's driven by the speedo output rather than the driveshaft. I think the T56 is 17 pulses per rotation and the 4L60E is 40 pulses per rotation of the driveshaft.

 

I think the electronic speedo is the way to go. Another reason why the PCM needs VSS is the reverse lock-out of the T56. The PCM must know the car is under 5 MPH before it will unlock the solenoid. One alternative is to wire a switch to the shifter, but I like the stock layout better.

 

6. I grabbed the underhood fusebox from the donor car which contains the fuses for the injectors, fuel pump, fan(s) and PCM power circuits along with the required relays. This made hooking up those items very easy.

 

A good idea, I'm not sure how the B-body wiring differs from the F-body, but I know on my TA, the fuse panel underhood is on the other side of the car from the PCM, and this would add a lot of wiring, plus you would still need the interior fuse panel from under the dash. I know my diagram has a lot of wiring, but I tried to keep it to the minimum to accomplish the install.

 

Hope this helps. If you want more specific info about how I wired things let me know and I'll see what I can do.

 

It helped a lot, this is the type of info I'm looking for. Thanks.

 

Wheelman

[240playtoy]

I found a VATS bypass module on ebay. bakerelectronicmakes them and other items that are useful. The thing works great and is less than $30. You just give the thing 12V power and hook the 3rd wire to your fuel enable wire and voila, cheap easy VATS bypass. Much cheaper than buying the module and it's tiny too. May not be cheaper than reprogramming your computer, but if you don't have any need to reprogram other than VATS, don't have to worry about package deliverers drop kicking your PCM. They've got them for LT1's and LS1's. (I've got a 93 LT1).

[Guest 73LT1Z]

That is good information, and a bargain. I'll edit the document once I get all the source info.

 

EDIT

I edited the document & added the Ebay VATS bypass relay as well as deleting some of the parts listings for the hook up wires.

[Guest 73LT1Z]

Document updated 12-10-05, added new info/diagram & wiring parts list w/ part numbers & prices, also a couple of more pics- warning- size is now 3MB for those w/ a slow connection.

 

Anyone w/ an LT1 in a 280Z, please feel free to offer feedback on this- my car is still in the concept stage so far as this goes, but at least I have most of the front end parts for it now and will be ordering the wiring stuff soon!

 

I was able to ID & tag all of the mentioned wires on my car except for the fuel pump- not an easy task as it came w/o a motor/trans & the harnesses & a few parts were just laying there...

 

EDIT 12-6-05

I updated the MS Doc & diagram again, added in the oil & water temp senders (missed the forest for the trees).

 

I've removed my Datsun FI harness along with unused wiring in the engine bay & located the fuel pump wire under the dash. All listed parts in the paper have been ordered, so I'll update here as I make some progress.

 

Work is still in progress.

[Guest 73LT1Z]

Updated original thread/links with new info.

[love-my-V8-280Z]

I too am working on a LT1 into a 280Z. Mine is a 78.

I have mounted the PCM behind the glove box, I have all the work done, I installed new gauges and installed the dash.. Turned everything on and several things are not working.

The motor starts but a couple gauges did not work and what not.. I was really expecting it to go flawless. I have put so much time into studing.

Anyway I made a new wireing diagram also. I did not use the GM plugs. I may have shared this with you already. If you are interested in seeing it, and giving any feed back I would be glad to send a copy.

My address is steenhagen at charter dot net..

[Guest 73LT1Z]

Yes, I think your diagrams were the colorful ones! I did my first systems test yesterday & realized I had the wrong wire going to the "ignition on" relay. I have since corrected the diagram to reflect this.

 

I got a Lincoln MK VIII fan & it just about sucked the radiator from the support . I've also revised the paper/diagram to make use of this fan since it fits the JTR radiator nicely and flows so well.

 

I'm really looking forward to the remainder of the conversion, and I'm sure there will be many more bugs (like when I realized I have NO BRAKES on the right rear wheel, the only one I hadn't taken off up to now, looks like it is time for that rear disk conversion), but each day I get a little more done.

[Guest 73LT1Z]

Updated the document 1-11-06, corrected the link in my original post.

 

Running into suspension problems now...

[gvincent]

73LT1Z, what a great thread!

I am just getting underway with my 76 280Z/LT1/T56 and this is the type of info I am collecting from this great site! I have copied this entire thread into my Wiring tech folder for the project.

Great info!

Thanks,

Greg

[Guest 73LT1Z]

Thanks for the kind words. I'm glad the links still work OK, it has been a while since I updated.

 

I am neck deep in my LM7 Supra project now so I can get it to start & drive onto the car hauler. The 280Z has some type of glitch in the PCM or wiring to where it shows an injector fault after it starts & runs- it will not re-start unless the battery is disconnected. I have not had the time to mess with it, besides which it is at it's new home with all my other 4 wheel kids except for the Supra.

 

The above stuff should get you to where you can get everything wired, I'm glad it has been helpful.

 

EDIT

Make sure you use Metripack or Weatherpack connectors (also available at Waytek) instead of the Mate-N-Lock ones- they are better units. I will try & revise the document to reflect this.

 

EDIT #2

I found where my problem PROBABLY is! I noticed after wiring my Supra that I did not have an orange battery feed in the Datsun wiring diagram. It was omitted from connector C100-D. I have revised the diagram and document to reflect this. Hopefully it will cure my non re-start issue.