NewZed

The engine sounded good but it did sound like the timing might be retarded a bit. Invest in a decent timing light, they're easy to use and not too expensive. Since the engine ran well with no major knocking noises and the oil did not look bad I'd say don't do anything drastic until you know more. Don't let anyone, or a youtube video, convince you that you need to replace head gaskets or manifold gaskets or whatever. Engines can have many small problems and still run well without doing more damage. Your main concern should be that you have good oil pressure, I'd assume that there is a working gauge, and the oil stays clean. Low oil pressure is the main killer of all engines. Most will survive the other stuff, but just run poorly in the meantime. Your title says "rebuild" but there are no signs that you need to rebuild anything. Besides oil pressure though, your other big concern is that that engine in a Z is just itching to get sideways and leave the road. Be careful.

Smoke coming from the engine bay, assuming that the car has a full exhaust system on it, is usually from oil on the headers, from a leak or from recent work. Headers get hot very fast and the oil will vaporize almost as soon as the engine starts. In your second video whatever you were scraping at is barely visible, and the oil on the rocker arm and top of the head doesn't look bad. It might be that you're just not familiar with what you're seeing. If the engine has been sitting a long time there might a small amount of condensation that will burn off as the engine runs. If you're really worried about coolant in the crankcase just drain the oil and see what comes out. If there's a lot of water it will separate from the oil. You'll get a layer of water then the oil. Or the oil will look milky because the water has been whipped in to it by the crankshaft. If you think that you might have coolant leaking in to a cylinder, just pull the spark plugs and examine them. Coolant is a great cleaning agent in a hot combustion chamber. You'll either have fouled plugs because of loss of compression and/or water, or clean plugs next to normal, or they'll look okay. But there will be signs if you have a problem. Coolant on top of the manifold probably has nothing to do with coolant inside the engine, unless the manifold i not seated properly. But if that were the case you'd probably have intake vacuum leaks also, causing problems with the engine running. Separate those two things in your mind. Good luck, the engine sounds pretty good, at least as far as phone cameras go. You might create a youtube page and load your videos there. Easier to share and they'll play faster.

No offense intended, but this is (a terrible way) not a good way diagnose an engine problem. The engine barely cares what's in the radiator. What's in the oil? How does the dipstick look?

Go for it. Take some pictures, it will be good entertainment. Are we talking Sawzall, hacksaw, file, grinder? Make a video. https://row52.com/Vehicle/Index/1N6SD11S6PC357322 https://row52.com/Vehicle/Index/1N6SD16S4RC354902 https://row52.com/Vehicle/Index/1N6SD16S0MC421925

That's a lot of machine work and parts sourcing just to get a couple of bolt holes to line up. And why do all of that work, then use "right stuff" to goop up any holes? If the Z22 distributor body is what you really need, with a splined drive end on the shaft the simple thing to do might be to swap the L28 shaft in to the Z22 unit, or modify the Z22 shaft. Cut it and lengthen it. But the splined end looks detachable anyway, so really it's just lengthening the shaft and reattaching the splined drive piece. Make an adapter to mount the body to the L28 cover. Don't forget that you'll need a trigger wheel on the top and a 6 plug cap if you decide to use it as a distributor also. In the end this is the same as the Jeep CAS or the Pathfinder CAS modification though. The overarching question is which is more rational and cost-effective - sourcing, buying, modifying, and installing a whole front cover (don't forget the crank snout seal and the water pump and its ports and the seal to the oil pan), or sourcing, buying, modifying, and installing a more readily available distributor. https://www.rockauto.com/en/catalog/nissan,1994,d21+pickup,2.4l+l4,1212084,ignition,distributor,7108

@cgsheen, I think, has written about other ways to get an alternative optical disc in the distributor. I think maybe a Pathfinder CAS/distributor was used. There are also threads out there about the Jeep CAS/distributor. A lot depends on what engine management you're planning to use. Nissan or MS or other.

1976 should not have points, it should have a magnetic pickup system. The GM HEI module is designed for that type of system that's why it works well in the Nissan application. The 0.6 ohm Flame Thrower should work well with the HEI module. Yours might have one or two pickups but you can only use one if you convert to the HEI module. The second pickup is for emissions purposes, it's not a big deal to swatch to one.

It depends to a certain extent on how you have the injectors attached to the rail. The Pallnet rail has the injector o-rings inserted in to a cavity to seal the top and uses the precisely machined mounts to press the bottom o-ring against the manifold surface. The bottom is not the typical o-ring seal, it uses downward force to create the seal. If you don't get the rail mount correct, and the sealing surface flat and clean, you can have a vacuum leak at the interface with the injector. Coincidentally, a typical o-ring style injector will project in to the flow stream of the L6 manifold at just about the perfect level for injection. Not too deep or too shallow. You don't have to use o-rings either, you can use the Nissan sealing rubber instead. A more typical aftermarket mount would fasten bungs to the manifold to create a technically correct o-ring seal. But the downward force method works on the bottom because it is only sealing intake vacuum, not fuel pressure. It's not ideal but it seems to work fine for a lot of people. You can find injector bungs everywhere if you want to be more correct. https://www.jegs.com/p/JEGS/JEGS-Fuel-Injector-Bungs/3318814/10002/-1#

If it was a problem the sag would happen with the doors open. If the point where the door mounts is deforming due to weight then the door hinges would bind. Can't imagine a problem with removing them.

I misunderstood the FSM, it seems that it probably adjusts to engine conditions, as they say. You said that you just wanted to get the engine running before removing it. Jumping the pump is the way to do that. Good luck, whatever you end up doing. Parts for the old ECCS system are hard to find so Megasquirt or other standalone is probably more dependable in the long run.

Is this a thing? "the clicking fuel pump relay syndrome" classiczcars.com has FSM's that you can download. 1981 is still primitive. I think the fuel pump just runs full speed all the time. Might as well jump it if you just want fuel pressure. Here's the section from the 1981 Turbo Supplement. You should get a 5 second prime, or you can pull the starter solenoid wire and use the Start circuit.

Do you know why it was parked 20 years ago? I think that it's fairly common for people to get angry when they can't get in to reverse, because of a bad clutch cylinder, and to force the shift lever. Damage to the fork seems possible. You can get to the reverse/5th fork without removing the front case.

I just realized a possible solution. A "cold air battery". CAB (trademark pending). Move the battery in front of the radiator. The extra leverage should drop the nose a bit.

I don't know how much modifying you want to do but here are a couple of links about replacing your ignition module and coil, and getting rid of the ballast resistor. All of which will give you a stronger and more dependable spark. These old ignition modules are dying at a regular rate after 40 + years, and the ballast resistors go bad also. It's easy to do and easily reversed if you need to. And pretty cheap. One of the guys is from your area of the world. https://www.classiczcars.com/articles/electrical/replacing-the-280z-tiu-with-an-hei-module-r67/ https://www.classiczcars.com/profile/25507-sscanf/

I kind of overlooked that. You definitely do not want to see sparks anywhere in the engine bay. The spark jumping to the negative terminal is definitely bad, it might be a sign of bad wires, or the center wire not completely seated in the coil. So you need to fix your wires for sure, make sure the center wire is firmly seated in the coil and the distributor. But you also need to check the rotor and the distributor cap also. Spend some time making sure those parts are in good shape. Even having your spark plug gap set too wide can cause the spark to jump to where it doesn't belong. The spark will take the easiest path to ground. One side effect though of the coil discharge jumping to the negative terminal is that it can damage your ignition module, since the negative terminal is connected to the module. Something to be aware of. But first, get some good wires, and tune-up parts and get the system to the point where the spark only passes through the spark plug wires. You should never see or hear sparks in the engine bay.

jonbill knows more about performance engines but it looks like the camshaft might have been reground. The base circles are close to the main shaft. You can measure lift if you want to be sure but it doesn't really matter much. Also you can see that the wipe pattern is close to the edge of the lobes, so the shaft has been out and back in and might be off a little bit. If you take your calipers and measure the area of the lobe that has no rise, then measure the lobe height, the difference should be 7 mm if it's stock. Big picture-wise though, you might as well just reset the lash to factory specs, and run it. No obvious problems there and the engines are generally durable.

Might be that your ignition module is going bad. When that happens extra sparks are created which also fire the injectors more often. Usually that will show up on your tachometer as erratic needle movement, excess RPM or a quivering/jumping inactive needle. Make sure that you marked the original position of the AFM vane, in case you find that the source is somewhere else. The AFM should never really need adjustment on a stock engine.

To jonbill's point, below. And if you post a picture of a few cam lobes a guess could be made about whether it's been reground or not.

One "trick" to increase cam lift is to run tighter lash. But it's dangerous, if a valve doesn't close completely it can burn/warp. Another possibility is "sunken" valves. Early gasoline had lead in it which lubricated the valve seats. When the lead was removed valve seat wear increased dramatically. It's not uncommon to find sunk valves on 240Z's, as I understand things. So, could be intentional, could be valve seat wear.

They're still working as the wheel drops in to depressions or one side of the car lifts. That's how progressive rate springs work, the weaker end will collapse faster than the stronger end. The problem people have is that the rates are wrong between front and back. With PU bushings there is no lifting effect from the bushing. So, it doesn't matter when you tighten the bolts and nuts. I think it's just a bad product. I don't know why people keep buying them. That's why MSA keeps selling them, because people keep buying.

You could have a 78 car or system, or a 78 engine and the sender wasn't swapped. But the two prong sender/switches were used from 78 on in to the ZX's. Might be that you got a late 77 with a 78 system. What is the build date of your car? It should be on the plate on the door jamb. Here is the 1978 system.

This comes up so often that it might get overlooked - make sure you tighten the suspension components with the car on the ground if you loosened, removed, or replaced any bushings. The factory bushings provided some "spring" to the suspension. And, because of that, if you wanted to get tricky, you could have a heavy friend sit on the front while you tighten the bushing bolts and nuts. The bushings will help hold it down. Edit - or you could lift the back while tightening. This is only an issue, and will only work, with the factory rubber bushings.

The Eibach springs seem to have more problems than any of the others. They're just inconsistent. Some sit too high, some sit too low, many sit too high in the front. some too high in the back. These stories have been cropping up for years and years. MSA keeps selling them and people keep having problems. Looks like some numbers might have changed slightly but it's still Eibach and MSA. https://www.zcar.com/threads/240-too-low-w-eibach-springs.293086/ Discussion Starter • #1 • Nov 6, 2009 Just recently got my 71' back on the ground. Installed Tokico HP Struts w/ the Eibach PR Springs from MSA. The front looks good, but the rear scrubs the tires (195/70R14) on any dip or bump. I have been searching alot on this issue. Most of the time it seems the springs were reversed or upside down. It is just not the case for me. Here's the rundown: Contacted MSA to verify proper installation: They state part # 6305.001 are the front springs and 6305.002 are the rear -- I can see the numbers on the front and they match. They state shorter coils should be at the top -- they are. They state the longer spring should be in the rear -- as I remember they were. However, I found one post where someone stated the longer springs went in the front???

Check the vacuum advance breaker plate while it's out. The ball bearings get rusty and stick. Don't force it, the plastic bearing retainer will break. Some people don't use vacuum advance with carbs but if you do you'll want it to move freely.

Mistake.