The rebuild of my Z.

Seems like the place to do this. As much of a thread for me to keep track of what the heck I'm doing as it is for you all to see.

Its a 1985 Nissan 300ZX, 3.0 SOHC V6, 2-seater, 5spd manual with t-tops. When I got it, the entire wiring harness had been mangled and, from the looks of it, set on fire. I re-wired a ton of crap and it ran flawlessly for a year. I think it was end of June last year, I tried to start it up in the garage and it simply wouldn't start. Had spark, had fuel, so I decided just to re-do the timing belt. With the help of some friends, accidents happened and long story short, the timing got set wrong so when i cranked it over, instead of starting, it just kinda bent the hell out of every single intake valve, and ruined the guides too. When I pulled it apart, the bottom end looked just fine, not even marks on the pistons. But the valves looked like:

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So now its sitting with the heads off, parts are ordered and should be here by the end of the week or next week, and I was going to document the build/rebuild. There isn't much you can get out of these things without a turbo, in terms of horsepower, but I really don't care whatsoever about power and build most cars for handling. As this one is already set for that, I'll throw in some things to give it a little bit extra in the power department. You know, enough torque to actually get the groceries home. That is if the bottom end has held up for almost a year.

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So, the quick list of mods before I get started, beyond the interior (custom gauges and steering wheel, stereo and other trinkets) are a Walbro 255 fuel pump, Tokico struts and Eibach springs, and full poly bushings. Also some XXR 17x8 wheels with summer directional performance tires, 225/45/17 up front (Nankang NS1, actually VERY grippy tire and cheap), 235/55/17 in the rear (Hankook Ventus, wrong size, but got em cheap, too much sidewall flex). According to previous owner, has a "stage 2" clutch but I don't feel it. Before it died, the thing handled like nothing I've ever been in. The grip was so high, my courage died before I could so much as squeek a tire on turns. I am not sure the lateral Gs but my battery kept spilling water from it. May have to pick up an Optima or something. Also has Brembo drilled/slotted rotors on all 4 wheels. And zero ABS. I don't know ow they made the brake system so good for a car of that time period, but if you step on the brakes too hard and you will dislocate your trachea. Has nothing to do with the rotors, but since those went on there is absolutely zero fade.

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Also has a cheapy sound system, good enough for me. A Sony head unit with some interior-matching 3-ways all around, and a 600wRMS @ 4ohm Class D monoblock with a single sealed cheapy 12" sub. Will probably end up changing that around a little.


Sooo the plans and what I have ordered:

The Exhaust. I had to cut one of the manifold pipes and another one runs 400$. Luckily the best bolt-on headers with downpipe I can get only cost 300$ so why not. Also got the cat-back to match it:

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Apparently the setup sounds great from all the reviews. Demo:



Next up, the standard rebuilt heads, making sure to swap my old cams into them, as they have a more aggressive grind to them.

Then comes a whole new intake manifold, in particular, a Pathfinder one, the difference is pretty obvious:

Old one looks like:

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New one looks like:

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Benefits are pretty obvious, and pretty much all the extra crap on the manifold is getting deleted, except the idle control. Beyond that will be a whole new custom intake as well instead of the 10-foot-long python of inefficiency it came with. Cleaning and painting of all the parts, and somewhere down the road, an aggressive cam setup and adjustable cam gears. And if something is wrong with the bottom end, higher compression pistons. But those are a long way off hopefully. Then onto the trinkets like the breather filters, EGR plugs and other happy crap. SO I will keep updating this over the next few weeks or however long it ends up taking so I know where I'm at and you can get a little window into it. Sorry for the long read.

nice, def keep us up to date on the build... Hopefully everything goes back together a little smoother this time around!

Im interested in this build too. Keep us updated. Sucks to hear about the timing issue but at least it didnt mess up the pistons.

keep it up!

This could be really interesting. I'm always excited to see non-V8 builds, even if it is a V6!

Nice another nissan! Welcome

Well some stuff came, still waiting on a pile of it but got my old heads out to swap some things to the new one and can't for the life of me get the bolts off to get the cams out, or to get the sprockets off. So may take a bit longer than expected as I don't have a vice or impact wrench or anything to help. Also looks like the old cams I was gonna swap in have some rust starting on the lobes so guess I'm gonna get some beefier cams now instead of later. Hoping it doesn't ruin the powerband which has always been pretty flat and nice low-down. Almost out of funds, though. Anyway, more info when stuff happens. This better work out, from all info I have been scouring, dynos are showing a leap of 130-180ish horsepower at the wheel with slightly less mods than what I'm putting in. Not getting my hopes up, just want it to work.

Just a small update, everything is pretty much here or on the way here to start the build except the cams. Tomorrow I'll send in mine to be reground, but it has a month and a half turnaround, so not much will happen in that time. But I'm glad I did it, since I just disassembled the drivers side rebuilt head I got and the cam lobes all had a ton of surface rust. Thankfully the rest of the thing looks OK. So the cam specs are: Stock 242 duration and .385" lift for both intake and exhaust, the new ones are going to be 270 duration and .427" lift. Will probably make it slightly lopey.

This is turning into more of a blog than a build thread, so here is a current pic of how everything is organized, and how messy my garage is:

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Another week, another set of pics for the blog/thread.

Headers coated to prevent rusting:

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The "platter" of parts being organized:

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I really hate this camera, but its all I can get my hands on.

Well its a sad day. My camshafts that I mailed through Goin' Postal using FedEx (and they never gave me a tracking number) have gone missing. Luckily my wife also threw away the receipt thinking it was junk. So now neither FedEx nor Goin' Postal will help me with anything, and there aren't any places that sell the cams anymore. The junkyards don't have any Z31s (the cam grinds are different for Zs than other cars with same engine) and I certainly don't have any more money to throw into this, so it looks like this project may be dead for quite a while unless I can figure something out.

Wow that sucks!!! Whoever you bought them from should have a tracking number. And cant they give you a copy of the reciept too?

Fedex can look up shipments by the ship to address if you know where it was dropped off. I went through that about 6 months ago.

I called FedEx and they told me they were not allowed to give me any info or tracking stuff. I'm going to check in to the place I mailed it tomorrow. Hopefully something can get resolved here, that was the last piece i needed to complete the build.

Oh I thought u ordered them.

Had to send in cores to get ground. Anyway I found the tracking number and it says they were delivered and signed for but the company I sent them to denies it. Hmmm.

Company fessed up to misplacing them and got things straightened out. They are taking my cams to Schneider Racing on Tuesday so looks like I'm back in business. Now I have an error in processing some studs I need from Nissan to deal with. haha this is going to be interesting.

Another random update. Got the studs. Still waiting on cams. Trying to dig up money for the last batch of parts (cap and rotor, timing belt, water pump, etc), until then been removing un-needed crap from the engine bay. Cruise control gone, most of the leftover AC parts gone, carbon canister gone, EGR crap gone. Is actually a lot of weight! I weighed them all and it came in at just over 100lbs taken out of the engine bay. If you factor in the difference in weight between the manifolds and the new headers and downpipes, with all the things I took off, it racks up to 136lbs. Before it died, I got the thing weighed and it came in at 2680lbs, so after all this crap it will be closer to 2550! *excited*. Then I'll put my 100lbs of subwoofer in and totally negate the savings But at least the weight will have moved from the front to the back.

The worst thing I figured I had to do was get the drivers side exhaust manifold off. Well I was right. Was all rusted together so I couldn't unbolt the parts. Had to jack up the car (could only do it a couple inches, gravel floor) and try and cut through the exhaust. 3 sawzall blades ruined, 3 pipes and 2 heat shields and 6 knuckles cut, I finally wrenched the damn thing out through the engine bay, a 4-foot long section with heat shield and part of the crossover pipe and downpipes and everything all the way back almost to the cat. Feels like a major victory. I doubt I'll be able to get to the mounts for the cat-back thats currently on it, to take that off, I just can't get the car high enough off the ground, but oh well. Will take car of that later. Open-header drive to an abandoned parking lot muahaha.

So now with all that settled, I have only 1 more AC line I'm trying to dig out. Then its clean up and assembly time when the parts are all here. Warm weather is nice.

awesome man.... gotta love the knuckle busters, seems like anytime I work on anything, I'm bleeding from somewhere lol

MotownG5 wrote:

awesome man.... gotta love the knuckle busters, seems like anytime I work on anything, I'm bleeding from somewhere lol

Haha true, its a great feeling though when you get through it. I keep a log of my mechanic-related injuries as a joke. And sorry if I keep going on in this thread, its partially something for me to go back and re-read after I'm finished and such.

no problem man, its pretty cool for me anyway.... that I can see and read about all the steps in the project... Man, I can only imagine how thick the book would be if I kept an injury log while working on vehicles lol

Nice build man! gotta love the Z cars! Good luck getting those cams.

Just putting in a quick note for myself of all the things that have gone into it before this build.

Eibach Springs
Tokico Blue Shocks
Brembo Drill/Slot Rotors
Poly Bushing Set
Wheels and Tires
Walbro 255 Fuel Pump
Wiring Overrides to keep the ECU from throttling the fuel pump
Sandwich oil adapter and new gauges (Oil Pressure, Volt and Narrowband)
240SX Short Shifter
(claimed) Stage 2 clutch
Air Filter
Magnaflow Cat and custom catback

Random Crap:
Steering wheel
Functional hood scoops (battery kept getting too hot from engine bay)
A stereo that doesn't suck
Conversion of interior from grey to black
Passengers Fender (was completely messed up when I got it)
Love-hate relationship with whether I want a wing on it or not. Actually got better gas mileage and noticeably more stability at speed with it so will probably go back on. But sometimes it just looks goofy to me.

Probably some other things I'm forgetting. Kinda sad that even after I'm done it likely won't even be on par with horsepower of modern V6 family cars. Oh well. But I guess after almost 30 years, the tech certainly has a gap.

/taking notes
/hoping the Xterra gets rear ended so I can swap the supercharger over to the Z

Follow-up for my records. What is about to be put on:

Air filter/heat shield
Custom intake piping
Long-runner Pathfinder intake manifold
W-series heads with better port design
Schneider Stage 2 Cams
MSA long-runner headers and downpipe
MSA Sebring Racing Spiralflow catback (still to be paired with Magnaflow Cat)
(possibly) Optima Battery
FPR pressure override bypass

Odds and ends and maintenance:
NGK wires and plugs
Extra systems delete (EGR, Cruise, SAI, AC, Evap) and engine bay cleanup
Injector harnesses and wiring
Water Pump/Thermostat
Timing belt/tensioner
Maxima distributor cap/rotor to clear intake manifold
O2 sensor
Fluid refresh (brakes, clutch, coolant, oil, gear oil for trans and differential)
All new hoses and belts
Possibly fan clutch


I think thats most of it. Looking at it like this, may take a while lol.

Some new random stuff.

The horrible exhaust manifold that almost stole my sanity:

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The rats nest from a previous owner that I can finally clean out:

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Working away on matching the new intake manifold to the other new parts:

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Still waiting for cams before I can do much else.

One last post today. This one actually looks like progress. A test fit of the drivers side head/valve cover/headers. Everything fits almost perfectly, the headers had to be coaxed onto the bolts a bit.

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