NewZed

Is the connector pinout at the ECU the same for a Maxima L24E compared to a ZX L28E? Curious if you can just swap the complete engine with AFM in the engine bay and the ECU in the cabin and be up and running with an L28, no funky tuning or tweaking.

Maybe you just got a bad nitriding job. Too thin, uneven, too brittle...

Did it backfire? Timing might be off. "I've got a 78 280z". What's the rest of the story? When's the last time it ran?

Squirt some starter fluid in the intake manifold (pull a hose) and see what happens. If it starts then dies, your injectors may not be opening. If it doesn't start then you may not really have spark to the plugs or you have fouled spark plugs, which also results in no spark. Edit - it may also be that your Honda avatar is bad karma.

Up to somewhere in 1980 the 5 speed has the same gear set in 1 - 4 as the 75 - 79 4 speed. 5th is an engineered add on. So it comes down to your desired freeway RPM or top speed, if you're considering the early 5 speed. If you want the more evenly spaced 1 - 4 ratios, they only come in the 5 speed anyway. That's the other reason people swap the later 5 speed in. First gear is different between the early and late 4 and 5 speeds also, so the rear ratio can be important. The very early 4 speeds, 72-74, have a much lower first gear to match the 3.36 rear ratio. All of the options have a 1:1 4th gear ratio. Talking about the transmissions available on the factory Z's and ZX's, not racing options. Ratios are listed around the internet and in the FSM's. Coincidentally, read Post #73 in this thread - http://www.classiczcars.com/forums/open-zcar-discussion/40249-hls30-01222-project-3.html

There's a lot of good information in this thread. Were you just being extra cautious with the nitriding? Trying to avoid the new camashaft disaster? The comment above looks like Kinetic doesn't recommend it, but doesn't recommend against it either. But does say that the standard finish works best which implies that they've seen both in action. Googling "estas camshafts" brings up some interesting web sites also.

You might have the hoses at the rail switched, in the engine bay by the filter. That would pump directly to the return of the FPR. Note - I've only verified that an Aeromotive FPR won't flow backward, not a stock one. But I think that the general concept of regulation is the same. The fuel pushes on a much smaller area in reverse.

Maybe you connected hoses backwards at the tank. Pumping in to the return line instead of the supply line. The FPR won't flow backward, so you'll end up with the 90 psi or more that most aftermarket pumps will produce. Ot it could just be a loose hose clamp. Doesn't sound like you've looked to see where the leak is. "a hose beneath the car"?

The links are sized to the amount of current that they're designed to pass. They come in different sizes. This site seems about right for you, although the information about the red links is incorrect and/or incorrectly applied - http://atlanticz.ca/zclub/techtips/fusiblelinks/index.html

Here's a good start. You're right, there used to be something next to that link holder. Probably worth your while to figure out what the PO did to those wires.

The center of the yoke has a raised, machined portion that fits in to the machined center of the diff's pinion flange. It's a tight fit. Beat on it from two sides with a piece of wood or plastic/dead blow hammer to wiggle it out. If you use a chisel in the gap make sure to file or grind down the divot you create so that the you have a flat surface when you put it back together.

Does yours need a change just because it's time or because it has shifting problems? Some of the newer "syncromesh" fluids are lower viscosity (~5W-30) than the older fluids. They're designed for today's transmissions.

Curious - did you check wipe patterns while you were working on it? I get the impression that the guy buys used parts, shines them up, assembles them in to packages (custom?), then resells. You might have a grab bag of parts assembled to make one engine, with little atention paid to the important details.

Measure fuel pressure and check your cooant temperature circuit resistance at the ECU connector - sqwawk, cracker...

Sounds like you have a NAPS-Z engine. The two plugs are for emissions purposes. This is probably the wrong forum for your problem, have you tried any of the Nissan truck or Pahfinder forums? These guys seem to cover a wide variety of Nissan engines - http://community.ratsun.net/ You could probably convert to carbs with some work, but would you be able to pass CA emissions? http://en.wikipedia.org/wiki/Nissan_Z_engine

Were they sparks flying at any time while you were working on it? Maybe you blew a fuse or burned a fusible link. You said the EFI relay works, how do you know? Have you checked for power to the ECU at the connector? Get a multimeter and check the basics. Power to the ECU, power to the injectors, power to the fuel pump while Starting (on the 280Z's you can disconnect the starter solenoid wire to test the fuel pump, I don't know how the ZXT system works). Make a list of stuff that's right and stuff that's not.

Compare your first post comments, above, to your last post. You seem to be losing track of what works and what doesn't. You have to be methodical and careful to diagnose engine problems. You're all over the place and not making sense, in just one day.

It would be good to see all of the details on both setups. Cam grinder, shaft material, nitriding on just one or both, break-in lube, oil used for the first 500 miles, ZDDP, etc. From what I see about nitriding, it's supposed to reduce galling. Metal to metal contact is always bad so maybe it's just oil quantity. I didn't see anything about oil type in the previous posts. Maybe the nitrided surface needs polishing before use to be effective, since it's too hard to wear in. I seem to recall that the process leaves a rough surface behind. Interesting problem. Edit - the nitriding process would good to know also, since there are several.

Can you up the idle speed enough to keep it running and get a timing number? Or get one while cranking? That's what I'd do.

I haven't built any engines in real life, only in my head. I just threw that out as something that might match the evidence, a brainstorming thing. I could be way off. Since everything is installed, it would be easy to measure how much room is left in the springs at maximum lift. Valve lash generally gets looser when hot, but it's hard to imagine what the springs and valves might do. You might find you have tons of room and can think about some other potential cause. It might be something as simple as poor heat treating on the rocker arm pads.

Maybe Gollum wrote too many words. The engine doesn't matter. Injector impedance must match the electronics of the EMS. Specify the EFI system - ECU, harness, car it came from, details like that - and someone might have an answer.

WAG on inline's problem - coil bind on the springs? Maybe after everything gets hot. Can't really tell from the straight-on picture angle but it looks like the wear is happening evenly before and after maximum lift, when you'd think that it would happen where the ramp starts and on the way up.

Crap. I hate being wrong. I thought the weird ones were used in 1970. They changed the transmission tunnel from the 71 to 72 model? Here's a link that might be helpful - http://www2.zhome.com:81/ZCMnL/tech/69-83TrannyShifterDrawing.jpg Sorry for the misinformation.

You might take another look at the EGR device. On a 1978 N47 manfiold once you block the top with a plate, the bottom ports don't matter anymore, unless the passages are rusted through. You only have to worry about the exhaust manifold supply line from the exhaust manifold, which you don't have. The turbo system could be different, I've not seen one up close.

Pretty sure that an M16 bolt with a notch ground in to the side will self-cut its own threads in to the inside of the pipe on the exhaust manifold. If you can't get the threaded portion out (I couldn't) and ended up breaking the pipe off. Might help if that's what you're talking about...