NewZed

The thermostat housings are interchangeable. Looks like probably the 78 housing in your picture. I think that the gauge uses resistance to ground, so measure resistance from the pin on the sensor to ground first to see if the sensor is good. If it is, work backward looking for a short. If it's shorted, you probably have a bad sensor. The description might be in Body Electrical under gauges. Or Engine Electrical. Should be in the 78 FSM.

Get it nice and warm and see if it's still smoking. From your other post - it could be two years of dead bugs or spider webs burning off.

Check fuel pressure. Check for vacuum leaks. Could be a lean mixture. Don't replace any more parts until you take some measurements and know that the intake system is well sealed.

Most 1978s have EGR, I believe. If yours had it, did you reconnect it with headers? If not, what did you do with it? You might have created a vacuum leak.

Have you communicated with Pallnet? A simple courtesy. He might have reports from others if there was a mistake.

The early 280Zs, up to 78, used a contact in the AFM to complete a circuit to the fuel pump relay, which is housed in the same case as the EFI relay, by the hood latch release lever. In 78 they introduced a system that used the alternator L circuit and an oil pressure switch to control a fuel pump relay. The FSM gives the details.

There's something odd about planning to swap a 350, then later an RB, when you can't get the starter to turn the engine over. I would guess that you'll run in to much tougher problems with the swaps. But these things do make the forum interesting...

Have you tested the starter off the engine? If the engine turns by hand, a good starter installed properly should turn it also. Did you replace with new, or replace with old? Maybe you got another bad one, or it bound up during installation. There's not much to a starter - an electric motor with a solenoid actuated gear. Two electrical components that work together. L28 or 350, they work the same way.

What does the voltmeter do when you try to start it? Does it go to zero or just drop a little bit? You might just have dirty battery connections, or a bad battery. Could be at the posts or between the wire and the terminals, especially if they're the style that clamp on the bare wire ends. You might have the same problem with the 350 after it's dropped in.

That tube is the PCV tube. It should just twist and pull out of the one block and press in to the one without. Looks like you might be getting ahead of yourself. You've bought another engine and pulled the old one and you don't know what you had before or what you have now. You could have done a compression test with the old engine in the car. Probably still could with the engine on blocks and the transmission and starter re-installed. You'd want to put the little notched retainer thing back on first though. Were you revving the crap out of it when it started running bad? That might explain why the thing, whatever it is, came off along with the rocker arm. The How to Rebuild book by Monroe is worth buying. $14 at Amazon. It covers the PCV tube and everything else. How to Rebuild Your Nissan/Datsun OHC Engine: Covers L-Series Engines 4-Cylinder 1968-1978, 6-Cylinder 1970-1984 [Paperback] Tom Monroe (Author)

These engines are known for having the oil pump gear off a tooth, which moves the distributor drive shaft off its mark also, putting you out of adjustment range at the distributor. You can at least eyeball a tooth on the reluctor (the six point iron wheel on the distributor) with the timing mark at 10 degrees, on the compression stroke. A tooth should be about centered on the pickup coil. Easy to do, and timing's important. Looks like you've done everything else.

You didn't mention timing. The backfires show that your ignition system functions. Check firing order, make sure the order is in the right rotation, CCW, and set your timing. 10 degrees is a good ballpark number. I once had an engine that sat for only one year and wouldn't start until we squirted about a teaspoon full of oil in to each cylinder. They were dry, so there was no compression. Another possibility. And make sure that every vacuum hose is connected, the oil filler cap is on, and the dip stick is in its tube. Plus no cracks in the AFM intake hoses. The crankcase and intake system have to be completely sealed so that all air goes through the AFM. If there's a leak to the crankcase, the PCV system will let air in and cause the mixture to lean out. A sign of lean is intake backfires.

You should get this book. It's probably covered along with a lot of other things you should know - How to Rebuild Your Nissan/Datsun OHC Engine: Covers L-Series Engines 4-Cylinder 1968-1978, 6-Cylinder 1970-1984 [Paperback] Tom Monroe (Author) http://www.amazon.com/Rebuild-Your-Nissan-Datsun-Engine/dp/1931128030/ref=sr_1_1?ie=UTF8&qid=1340052817&sr=8-1&keywords=how+to+rebuild+nissan

http://www.liveleak.com/view?i=d2f_1339964794

Somehow I found that link. It's buried on the Atlanticz.com page, the only place I've seen it. Might not be your problem but still very informative. http://atlanticz.ca/zclub/techtips/fuelpump/moreinfo.htm

Read the FSM, it has more detail specific to 1978. Fuel pump relays are probably described in Body Electrical or Engine Fuel. Somewhere out there on the internet is an account of how the 1978 safety system of the oil pressure switch and the alternator output can actually fail itself and cause the fuel pump to run continuously. If I find it I'll post a link.

Most yards have a return for credit policy. Worth asking. They hate giving cash back, of course. Pretty sure that the only difference in the 300Zx long-nose R200 CLSDs and the open diffs is the pinion flange. So your CV splines should plug right in to the 78 R200. I know that 1983 CVs do since I have a set and some R200s. It's implied also, in the Diff thread, since only the 1988 VLSD is the one with the different spline count - http://forums.hybridz.org/index.php/topic/49194-differential-cv-lsd-hp-torque-r160-r180-r200-r230-diff-mount/

Somebody would probably trade you a good NA motor straight across, with some cash, for that turbo motor. You'd probably spend more money on the machine work and parts than you would just buying another engine. The turbo engine should have a turbo cam also, which wouldn't be optimum for NA. Just an opinion. Edit - you could also swap the P90 head for an N47 head and get the 1978 engine's compression ratio, since the turbo engine will have dished pistons like the 1978 engine. Plus you'll be able to use your round port exhaust manifold, which is not recommended for square port exhaust. Just thinking...

If you look at pages 50 and 66 in the Engine Fuel and Emission Control section of the 1982 FSM, you'll see actual words from Nissan of the fuel pump relay being "on" for either a few or 5 seconds. There is also a diagram on each page showing the ECU connected to the relay, not the pump. So far, it is the only official publication, described in any of Heroes' threads, from Nissan that verifies power to the relay that controls the pump for a short time without the engine running or in Start mode. No mention of why or if it has a purpose. State of the knowledge of the mystery.

Page 50 and 66 (as you noted) say the pump turns on for either a few or 5 seconds. Those are the only two mentions of a "priming" function that anyone has found and reported. I'm assuming that when the FSM says the relay is on that it is feeding power to the fuel pump. Otherwise the pump would run when the key was off, since the circuit runs directly to the battery +. That's what the diagram implies since the pump has its own ground. It is a puzzle.

That's a good find by ctc. Even better, the FSM seems to imply that the EFI ECU turns on the relay for a "few seconds", page 50 description of the earlier, non ECCS EFI. The diagram and table seem to say that the ECU "monitors" engine RPM by coil pulses to control the power to the relay, but that the relay is energized for a few seconds when the key is turned ON. Seems like the computer is the controller, at least for 1982.

You should start your own thread. http://www.urbandictionary.com/define.php?term=Thread%20Jacking

Your title implies that you're looking for a 240SX trans already converted, but your message says you're looking for a belhousing/front case from an L28 trans so you can do your own.

Raising your idle speed will help. The alt output at low RPM is very low, a hundred RPM makes a difference.

Oh well then. I thought you might be depending on closed loop control to get the mixture right. Good luck with it. You'll probably just have to go through the tedium of doing all of the tests in the FSM.