NewZed

You could have torqued the bolt to 100 ft-lbs by now. Easier than all of the words, probably, and will tell you more. Good luck. p.s. cutting a groove like that is almost exactly what you would do if you were trying to remove a stuck bolt in a tube and heat didn't work. The metal stretches at the groove and the bolt is freed. Same concept as cutting along the length of fuel hose stuck on a barb. It releases before you get all the way through.

Your plugs are either oil-fouled or fuel-fouled. But they are not lean-fouled. Make it leaner. If it doesn't run right because you're too lean then maybe you have a ring-sealing problem. I'm sensing subconscious "I just rebuilt the engine it can't be the rings" thinking. Just a suggestion. And, like others said, get some known plugs in there. Those multi-electrode plugs are gimmicks. The basic concept ignores the fact the fuel-air mixture is moving rapidly past the spark point. It's not a static situation. All that extra metal cools the electrodes also. The electrode (ground strap) needs to get hot and stay hot so the carbon burns off. Gimmick.

The tube is a fine thread precise fit. It's a dilemma. Welding one side will probably warp it enough that the bolt might not fit anymore. Put some thought in to a plan.

The metal tube does not rotate around the end of the arm. The rubber flexes instead. That's why you're supposed to tighten the bolts with the weight of the car on the suspension. A picture of the end would be better. Thread the bolt in and see if you think there's enough metal left to hold the torque. 100 ft-lbs. That's the real concern. If the tube splits and the bolt loosens the control arm will get loose.

White smoke does not come from "lean". You're starting from a bad assumption.

Not normal. What size tires? What type of pad? I think that ceramics have a lower coefficient of friction. https://ctbrakes.com/brakeanswers/friction-compounds/ On the back I found that typical parts stores shoes are meant to fit a larger diameter drum. Only the ends contacted the drum when used. But the back tires still locked up when I was having front brakes bleeding problems.

More fuel or less fuel? "fingering' doesn't really tell much. I don't think the engine will run on one cylinder. So, it's still not clear what you mean. Don't overlook the simple "fouled plugs". When the cylinders don't fire the plugs tend to get dirty. Plug examination usually tells a story. And - bad fuel.

If it was running great before the first thing you should do is to put the AFM back exactly as it was before. "Adjusting" AFM's ruins most of them. Nissan puts glue on the wheel because they're only meant to be adjusted when calibrated then never touched again. One cylinder must be an exaggeration, right? Post a video. Are you sure that you didn't bump something or do something that you think "should" have no affect? Because there's nothing you've described that is a clue. "Engine ran great, worked on engine, engine runs terrible" is all that's here.

Vapor, gases, "air" that was dissolved in the gasoline (it's a thing) but degassed when the pressure was released...I should have been specific. But, as someone who had an Aeromotive FPR for a while I know the sound of "non-liquid" being pushed through the rail and back to the tank when priming the system. The rail empties of liquid and fills with non-liquid, vaporous substance. The injectors are very hot after an engine runs and just percoate the liquid out until they are dry (I assume). Then the new fuel has to come back in and refill each injector and pressurize it so that it will squirt the proper amount of liquid out when the injector opens. Or, in short: no leakdown = quick no-prime start; leakdown = prime ,wait, start after extra cranks, and maybe some rough revolutions before things smooth out. It's really just where a person wants to be on the daily driver/race car spectrum. I got tired of priming and waiting so modified a Bosch regulator, for convenience.

The issue with the pressure bleeding off is that restarting the engine after a day or two is difficult. The fuel rail typically empties due to the heat from the engine. Even if you prime it it's still full of air bubbles. Besides that, if you're going to prime then you have to add another switch to run the pump. It kind of boils down to how involved a person wants to be in getting their engine started. An FPR that doesn't leak down will start faster than one that does.

Does it hold pressure when the pump is not running?

There is a vacuum port on the FPR that increases or decreases fuel pressure based on intake manifold pressure. The factory Nissan turbo system uses a simple FPR with a reference vacuum/pressure line. It maintains a constant pressure so that the ECU can adjust injector flow rates accordingly. Here's a description. https://www.haltech.com/why-you-need-a-fuel-pressure-regulator/

If you're using 440cc injectors you must have aftermarket engine management. So you don't need an adjustable regulator. I'm a big fan of factory designed parts, they're made to do things like hold pressure and last 100,000 miles. I'd just find a 2.5 or 3 bar factory FPR and plumb it in. Actually I'd go with the higher pressure to combat heat soak problems that the Z's tend to have. Example below. I don't know if that's 3 bar or not but the form seems right for what you're doing. https://www.rockauto.com/en/catalog/bmw,1985,325e,2.7l+l6,1011643,fuel+&+air,fuel+injection+pressure+regulator,6124

Here's an interesting thread. It's funny how people who don't have the problem think they understand it better than people who do have the problem. People are strange. https://ls1tech.com/forums/fueling-injection/1830922-want-aftermarket-efi-regulator-holds-pressure-key-off.html

That's a salesman who found out that it doesn't hold pressure so answered a question that you didn't ask instead. "Fluid in the lines"? C'mon. "Tech staff" is probably one guy, maybe even the same guy you were talking to, switching hats. All of those aftermarket companies use the same design, a ball-shaped valve in a large round seat. They just don't seal well. I tried to find a price for those Bosch parts on the internet and they seem spendy. And I only found a place in Australia that sells them. But a call to the local Mini dealer might get better results. Good luck.

I had an old style Bosch adjustable regulator with hose barbs that I modified to have a vacuum reference. Here is Bosch's modern version that already has a vacuum reference port. Mine did not leak down. It acted like a normal modern car FPR which does not leak down. Edit - I'm not really sure how it's plumbed in to their system. The flow happens between the O-rings. But it might give you some ideas. https://www.bosch-motorsport.com/content/downloads/Raceparts/en-GB/50154251144125323.html#/Tabs=50170635/ Edit further - actually they have an adapter. If I had the money and was building a system from scratch I'd probably go with the Mini A and the adapter. A person might think that priming the rail before every start is no big deal but being able to jump in and turn the key is much better. https://www.bosch-motorsport.com/content/downloads/Raceparts/en-GB/50225163113309707.html https://www.bosch-motorsport.com/content/downloads/Raceparts/en-GB/109952523.html

Most of the nice looking aluminum FPR's leak down almost immediately.

A good FPR should hold pressure.

The factory FPR is not supposed to. But they can fail after many years. It's not uncommon but it's not correct either. You can find pressure in fuel rails on 280Z's and ZX's in the wrecking yard.

That is common. They are not designed to hold pressure. Search the internet for "aeromotive FPR not holding pressure" and you'll find a ton. I had one for a while. Example - "I called Aeromotive about this and they confirmed that their regulators will not hold pressure when the pump is not running. (Dumb." https://www.pirate4x4.com/threads/fuel-pressure-regulator-that-acually-holds-pressure-when-the-pump-is-not-running.2057202/

If you have some stiff small diameter cable you can put it in a drill and use it to bore holes and clear passages. Like snaking a sewer pipe. It will pass through some bends. It does look like a bendy path to the opening inside the tank, here are some good pictures. At least you know what you're dealing with now. http://www.atlanticz.ca/zclub/techtips/fuel/gastank/index.htm

I reported your post so that whoever is doing the admin'ing can take a look. Hopefully they don't just delete it. If they do, my apologies. p.s. I'm not a real moderator. One of them just gave me that name.

Are you sure that you have the return hose connected to the proper line? There are vent lines over there too. It's not the pressure that would cause problems but the volume. The 280Z has lines designed for 30 GPH. The typical aftermarket pump will hit 90 psi. Like the Airtex E8312. I had that on my 76, with no problems. People run the Walbro 255 with no problems except noise. That's 67 GPH. It's unlikely that you'd have a restriction due to the design of the return line. More likely something got stuck in the hose if the connections are right. I'd doublecheck connections all the way back to the tank and in to the tank. Looks like you're on the right path.

When you say would not start do you mean that it would not stay running or that it would not start at all? If it just won't stay running, you might still consider the fuel tweak, or increasing pressure with your FPR. The AFM needs to have the correct rate of movement of the vane with air flow and that's what the atlanticz procedure is supposed to do. If the vane spring is too loose it will open too quick and run rich as soon as RPM increase, if it's too tight it will open too slowly and run lean. Get the rate right and use fuel pressure or the sensor mod to change the overall fuel mixture. If you think that it's running rich make sure that your FPR is not leaking through the diaphragm. They can do that and still show correct pressure. Not clear what type of FPR you're using. Make sure it has the vacuum hose attached also. It's important for the 280Z EFI system. Good luck.

Have you adjusted valve lash and checked cam timing (notch and groove)? Is the distributor in good shape, including the mechanical and vacuum advance mechanisms? Is ignition timing set correctly? The other way to increase fuel is through the coolant temperature sensor, another Atlanticz tool, linked below. Or just raise the fuel pressure. And if you're using old injectors it might be that one or two are not flowing at full rate. That will give you lean cylinders. You can't fix that without installing a set of balanced injectors. https://www.atlanticz.ca/zclub/techtips/tempsensorpot/index.html