Zed Head

I am going to second CO's proposal, but without even the "smoosh" to make it more round. It's just a vapor line. It might even be the one with a check valve in it, and the check valve is probably the main constriction. Have you checked operation of that pump? If it's original, it's old.

Good luck with this method.

If the engine ran before, and the wire was cut before, then it would not be the problem. Seems like you're focused on something that probably doesn't matter. Do you have a meter? You need to find out where the power is and where the power isn't. The ignition relay is a good starting point. And the fusible link. It supplies the relay, which passes the power on to the harness. With a meter or a test light you can find out where the power is not getting through. This is just one diagram of many in the Electrical chapter. With wire colors. Locations are in another part of the chapter. You just have to get in there and poke around. Don't forget to double-check the battery connections. They can be tight enough to run the meter but loose enough to open up when the starter draws a lot fo current. They need to be tight and clean.

Did you cut the wire? There is a factory service manual available for free download. https://www.classiczcars.com/files/category/14-280zx/

Did you actually measure and see this amount of variation or are you talking about the specifications in the FSM? Timing can swing by up to 40 degrees or more with one throttle press, on an engine with common timing controls. The emissions controls typically just affect idle timing. Since you don't drive at idle it won't affect performance.

I'm thinking that you have, basically, an L26 with a bigger than stock valves. Here's an engine calculator to play around with. Looks like about 8.3 CR,which is 280Z L28 range. The head doesn't look shaved, the letters still have a lot of metal under them. http://www.ozdat.com/ozdatonline/enginedesign/ I would check valve lash and the wipe pattern on the rocker arm pads. People make mistakes, or sometimes just throw a bunch of parts together. The N42 head's valves would hit the sides of an L24 bore, unless the bore has been relieved. Might want to turn the engine carefully by hand to be sure there's no interference, before using the starter.

Edit - maybe call that machine shop and see if they have records. The tag has a number. The longer stroke crank started with the L26. So, it could be an L24 stroked out to L26 size. The rebuild tag could be an old one of course, but .030" is a common overbore size. Here are the stock bores and strokes for the three engines. And piston types, as I understand them. L24 83 x 73.7 flat tops L26 83 x 79 dished L28 86 x 79 dished

The original engine size should be stamped on the flat spot above the #6 cylinder, the back one, on the right side of the engine (passenger side in the States). The cam looks like a stock cam, the base circle has not been reduced. The tag from the rebuilder makes it look a like a .030 overbore, so 3 liters seems unlikely. I'm going to guess that it's an L26 that's had an L28 head installed. The L26 had dished pistons, as I understand it. Using the N42 head is probably a simpler way to get bigger valves. The gap between the lash pad and the cam lobe is sign of a loose anti-rattle spring (aka mouse trap spring), I think. Not a huge deal.

Probably just swapped an 81 turbo damper on to his L24. They'll interchange.

I'd rather hit a big soft bug than a small hard one. Who knows what will arrive. Hope they're good. Pilkington is one of the OG glass companies, but, as we all know, brand names get sold, and the quality can get left behind. Let's see. https://en.wikipedia.org/wiki/Pilkington https://www.pilkington.com/en/us

Several of us have found that the main problem with the aftermarket or reman hydraulics is that they're dirty inside, with machining swarf/grit left over, that will eat the new seals pretty quickly. Just disassemble and clean them and you'll probably be fine.

Here's one option. You'll probably have to contact him, I can't figure out what, exactly, he's selling. He tends to make good products though. Web-site skills, not so hot. http://hokeperformance.squarespace.com/store/l-series-crank-angle-sensor-kit

Looks like a 1981 turbo engine damper. Might even be an L28 in that 240Z. The wheel is there but where's the sensor? See picture. Nissan used the crankshaft mounted wheel for one model year then went to a distributor based system. But there are a few aftermarket systems out there.

Did a Google for giggles. I'm tempted now. Need that shaded upper edge. https://www.summitracing.com/parts/pkc-400046793/applications

The edges of my pedal box are mangled by a PO who had that same problem, trying to make more space with a pair of pliers. I still had problems with that pin. I ended up tying a thread through the hole in the pin, then using a thin wire to fish the thread through the holes, eventually pulling the pin up to the holes by the thread, getting it to "stand up", and pushing it through the holes with a screwdriver. Overall, an intricate operation. More planning than doing, in the end.

The details that JSM asks for would help. Plus a bunch of others, like how long have you had the car, did it run before, why did you rebuild it, etc. But, your finding that the coil neg needs to go to Pin 1 puts you ahead of many (no offense to many). The wire to the ECU should already be there, in the engine bay. There is no need at all to remove it. It's blue. It's also connected to your tach. Don't overlook that the injector power is on its own circuit. The ECU doesn't "signal" the injectors, it just provides a ground so that the power can pass through them. Here's another link to the book JSM tried to.

I edited my confusing posts above... Probably more confusing now.

Darn it. I got your diff confused with your transmission. Diff fluid is easy. GL-5 is fine, just make sure it's for differentials. This is for your transmission: (Edit - I wrote all of this because I'm using a GL-5 in my transmission and it's been fine. Swepco 201). But that's a whole other story) There is a ton of stuff out on the internet about "GL-5" and "yellow metals" and mass destruction. Probably all derived from one guy whose transmission had problems after he changed transmission fluids. I've only seen one story from the person who actually had problems, and he was in the middle of a race. I think that the real bad actors are the extreme pressure (EP) additives used in differential fluids. The GL-5 spec. is just a specification and tells nothing about what's in the fluid. It's a red herring. Just get this MT-90. It's the one everyone uses. It's GL-4 and it works great. https://www.redlineoil.com/mt-90-75w90-gl-4-gear-oil https://www.amazon.com/Red-Line-50304-Transmission-Transaxle/dp/B000CPCBEQ

Yes, the N42 block was used up to mid-1980 I think, through 1979 for sure. The heads changed to N47 heads sometime in 77. That might be the confusion. N42 heads were used in 75 and 76 cars. But, my 76 has a 78 engine in it. Because I put it there. And I have an 81 engine in the garage for if that one fails. Engine swaps are easy, and that car has seen some work done on it.

Not sure where you got that picture, but that's not the spec for an old 280Z or 280ZX 5 speed. The MT90 will work great, the Synchromesh probably will too. Here's the 1983 280ZX spec.

That actually looks like a 77 or 78 280Z. The metal trim piece on the back is a clue. 75 and 76 had rubber. So, if it is, the door parts should fit your car. The door handles, for instance. They break, and they're hard to find. The trim pieces on the door card. The rear view mirror inside. Did anyone mention the half-shafts? From the diff to the wheels? They're pretty easy to remove and if the joints aren't dried out they can be regreased and will last another 50,000 miles probably. Actually cheaper than buying new parts store u-joints. 4 joints x $20 each = $80. I have a bunch of halfshafts in the garage, greased up and ready to swap if a u-joint goes bad. I think that the used Nissan joints are actually tighter than new Precision joints. They're shimmed to perfection. Even the main propeller shaft would be worth getting, since it's not a 75. 75 has an odd unique diff bolt pattern. They didn't use it again until the 300ZX's. The 280Z's don't have replaceable u-joints so a spare propeller shaft is nice to have. They're small too.

Early on when we became aware of the 123 there was discussion about whether or not it was "high energy". High energy systems typically have current-limiting technology in the module, which the latest version does. It doesn't require ballast either. It looks equivalent to the GM HEI module, or any 280Z system after 1978. I think that the early 123 systems weren't current limiting systems. The Hi-6 is a multiple spark system at low RPM. So it might give better idle performance than just a single spark system. Probably depends a lot on what type of engine you're using. Carbs and cam would benefit, EFI maybe not so much.

Both of those cars are somebody else's uncompleted project. The first guy is just getting out of the Z world and selling all of his parts, the second guy is trying to get back the money he spent. The first guy was trying to get back money spent also. That's why you might be better off just finding an old original Z. Then you can start spending more money than you can sell it for when you're done. And as pddenno implies, what are your plans? Many of us like to work on our cars (some have never driven theirs), some have completed cars for driving and showing. Are you looking for a project, a daily driver, or a race car? But if you don't know how to drive stick you might want to learn that first. It's not too hard but learning on a car you're thinking of buying isn't a good idea.

Go to the transmission end, remove it and see what's going on. It sounds like it might be loose on the trans end.

The consoles crack and break and get ratty. Maybe he just threw his away. I thought you were selling, not buying. You didn't make it clear that you were just copying the seller's ad in to your post. The mods on that car are not complex. You could buy any Z car and make it look like that. I would never buy a car without first driving it and examining in person. Good luck. It looks like a common modified old Z car. Remove the bumpers, put some wheels on it, tint the windows. The front air dam looks different though.