Sbc Z31

[WhiteHorizonZX]

Hi guys, I've been reading this forum for weeks now, looking into things & exploring this aspect of the Z world, and I believe I've been changed. I've got an '86 NA Z31 that's just pathetic. The car's sat for a little over a year now, and hasn't been run since june 'till today. I miss my Z, but there's too many problems with my electrical system that are far beyond the point where I can just fix it. After investigating my problems, it's become apparent that I have a chassis short, and I am just not willing to rip apart the interior to replace a length of wire. Here's the fun part. I'm enlisting into the US Army National Guard in March, I'll be back around the begining of this fall. I don't entend on being deployed but it's possible... anyway, that's beside the point. I'm coming into a good bit of money at that point & I've been wanting to work on my Z for some time. Now before you guys rant at me for not looking into this, I have, but there's not many resources. I know there's one guy on here who decided to drop the VG out of his '84 into a rat rod, and throw an sbc into the '84. I know that Dr. Buddah has done the sbc conversion to his z31 as well. Everywhere I look, I continue to hear that it's extremely difficult, & very costly. Well, I'm a frugal type of guy & I like to about things from the aspect of "what can I get without blowing my wallet", I think we all think that way from time to time, but I'm just looking for a little insight, some helpful hints, & a little information if you're so willing to give me such. Feel free to PM me too.

 

 

Pvt. Dear

[Mike kZ]

First off Welcome!

I would try to fix your wiring problem first. Even if you drop in a V8, you are still going to have this wiring problem, unless you plan to rip it all out and start over ( expensive and a pain in the butt.).

As you noticed there aren't many Z31 V8 cars. I would try and email all those that you found and start asking questions

Good luck!

[wingman]

I'm in the process of putting a 350 into an 88 Z31, and I'll be sure to keep a notepad of instructions for anybody that want's to know. I know Alf made a brief walkthrough of the conversion, but everybody uses a different tranny so everybody's will be a bit different.

 

I plan on keeping the stock AC and power steering, so I'll try and get bracket dimensions of the pieces I have made, as well as wiring instructions if I can get them to work. Like said before there aren't many SBC Z31's out there, so be prepared to figure out a lot of the stuff on your own.

[WhiteHorizonZX]

Sounds great, I can't wait to see how yours comes out. As far as the wiring goes, I want to use an 18 circuit fuse block from Painless, & integrate the painless wiring harness into the ecm (been planning on using an LT1 & the BW T56, but that's not deffinite). I probably should have mentioned it in my first post. But yes, plans are for new wiring, LT1 & 6speed trans. I intended on keeping the differential (seeking VLSD replacement) & CV's, unless someone disagrees.

[wingman]

ah, fuel injection adds a whole other monster in terms of wiring, but if you ask me it's more than worth it in the end. I hate chasing down electrical gremlins, and for what I'm after with my engine a carbed setup will do just fine, but otherwise I'd have definitely gone fuel injection.

[Alf]

WhiteHorizonZX, the SBC Z31 swap is totally do-able by the novice builder, sure you can't just order a kit out of a catalog and bolt it together, but with some ingenuity and patience it can be done. This being said, you need to either have the skills to do fabrication work or find someone who can perform these tasks for you. Even at that, there is only minimal fab needed, of which engine mounts and the transmision crossmember are the big ones.

 

Depending on what transmision you go with the difficulty may vary. Personaly, I would use the BW T-5, which may even line up with the shifter hole. I used a Saginaw three speed in my car for the sole reason that it was free, because I already had one. Some heavy shifter modifications where needed to make it poke through the floor in the original location, and any older non overdrive manual will be the same: Muncie M20, M21, M22, T-10, Super T-10, Saginaw 4 speed.

 

Another problem with the older three and fouur speeds is the lack of factory hydraulic clutch set-ups. After about a week of mimmicking Dr. Sues in an attempt to adapt the Nissan slave to the SBC with an over elaborate bracket, I bought a hydraulic throw out bearing. Hydraulic throw out bearings aren't cheap, they also aren't very much fun to adjust either. If I had a steel bell housing I could have welded a bracket right to the bellhousing and bolted the slave cylinder to it, maybe I'll mess with that more in the future.

 

You will also need to have a driveshaft made, which is one of the more expensive aspects of the swap. Instrumentation is another obstacle, the only guages that work in my car are the volt meter and oil pressure. The factory tach and temperature guages run through the computer, so once it's gone, so are the guages. The speedo does run off a cable, so it could most likely be adapted.

 

Because the Z31 chassis was originally home to a V6 rather than an I6, the engine bay is a little tight. The main problems come from the exhaust, especially on the drivers side, and hood clearance. I used Chevy "rams-horn" manifolds, which fit fairly well, Chapparell has block huggers on his.

 

The odd setup of the factory radiator is another problem. I purchased a new turbo radiator for my car and I ran a 16" electric fan (you must run an electric fan due to space restrictions). My car always seemed to run hot, but it never did overheat.

 

Here's a rough price breakdown on my car:

85' 300ZX: free due to fire damage

305 SBC and Saginaw 3 spd.: free, mainly because the engine was worn out and the transmision is just not very desireable

radiator: $130

Driveshaft: $211

Hydraulic throwout bearing: $180

misc. parts: $500

 

I'm sure there's more, I just can't remember, it's been a while. Basically I have about $1,500 total into my car at the moment.

 

Another important thing to note is that I have proven that this is a reliable swap. In the period of one year I drove my car about 6,000 miles, which includes three trips from New Jersey to Kansas, and I never had any serious problems, it never left me anywhere.

 

Here's a few links to some other threads:

 

http://forums.hybridz.org/showthread.php?t=108065

 

http://forums.hybridz.org/showthread.php?t=104866

 

Wingman, do you have any pictures of you project you could post?

[WhiteHorizonZX]

Alf!!! Hah, this goes right back to the idea of doing research, I came across a fair ammount of information you posted on this, yet I mearly looked over it & looked for key words, I'm sure you realize that I didn't actually "read" it by now. Thank you for this information, I'm very appreciative to have some real bed-rock assurance that I'm not just imagining things. If you don't mind, I'll take some time to list some ideas and plans that I have for the Z.

 

I'd like to use a Painless Wiring 18 circuit fuse block and run all my own wiring.

 

I had invisioned using a camaro/vette/firebird LT1-T56 combo out of an existing donar car. This is quite possible as they are easy to find in parts condition in my area.

 

I assumed that because the T-5 that is already in use in the vehicle & the T56 were close relatives that it'd be a simpler swap, but I expect complications.

 

I plan on removing virtually all the existing electronics in the vehicle & replacing them with newer, aftermarket parts. Like Autometer guages, retain the factory power windows & locks, make use of the donor car's fuel pump (and if that doesn't work, I'll go ahead & spend the cash for an Aeromotive pump), I have not yet figured out what to do about heater control. I was hoping to buy a GM sending unit & integrate it into the new wiring.

 

I also had a new idea today as I was thinking of the same problem you expressed about temperature, I believe that if I used sheet metal to "duct" the radiator (I.E. creating an opening similar to that of the existing opening in the '86 model, using aluminum sheet metal), and then continuing the ducting up through the hood.

 

I am not decided apon what type of exhaust headers I want to use, but I know I want to use headers.

 

I have a unique idea for the exhaust that resembles that of the 350Z exhaust muffler.

 

I am open to any and all suggestions, thank you very much for being so helpfull!

 

Pvt. Dear

[wingman]

alf, nothing is on the car as of yet, I'm still in the parts gathering phase. I'm doing a full car build however, so it's taking quite a bit longer than just an engine build.

 

I am going to do a bit of chopping though, I plan on running a dual exhaust setup so the spare tire well will be hacked and re-welded and an area of the body above the subframe on the passenger side will be hammered in to clear the exhaust. I'll be using block hugger headers at very minimum, I may go so far as to have some custom fabricated if I'm not happy with them, however.

 

I'm not 100% as to how the tachometer will function, but would it be possible to use an MSD tach adapter in place of the ECU? or even keep the ECU only for tach, temp, and air conditioner purposes (that is, if the computer has an A/C idle up). Just disconnect the warning lights in the dash since they won't matter anyway.

 

I'll also be cramming a larger radiator in the front than the stock '88 turbo. We have quite a few cores sitting around at the shop where I work so it's prettymuch as simple as finding one that fits and making some brackets.