NewZed

4th gear doesn't use the countershaft, it's direct drive. That's a good clue. Sounds more like the countershaft bearing. Looks like you'll need to split the cases, so you might as well do the mainshaft/input shaft bearing also. It's not a super-finesse job. Just needs some ingenuity. It's fun. Part of Z ownership. Here's a good illustration of the parts you'll be looking at. I'm sure that there are "how-to" videos out there somewhere. You can get a factory service manual on the internet that shows how to take it apart. Good luck. https://www.zhome.com/ZCMnL/tech/240SX5spd/Transmission2.htm

"Grinding" is not very specific. Can you add details? Have you driven it? Is it the same in every gear? 71B's are known for destroying the adapter plate bearings. Did you find any metal on the drain plug magnet? If you've been driving it you might drain the fluid and see how it looks. Might also be worthwhile to lift the car and get underneath with the engine running to see if you can locate the noise. Replacing the main and countershaft bearings is not very difficult. You only have to split the cases and pull the bearings off of the ends of the shafts. The adapter plate bearings are more difficult.

Probably, but it must be an old one. https://www.centerforce.com/i-30500105-centerforce-i-clutch-pressure-plate-and-disc-set.html#!submodel%3DBASE - 2.8L - PRODUCTION FROM%3A 12%2F01%2F74 - PRODUCTION TO%3A 05%2F31%2F78||model%3D280Z||make%3DNISSAN||year%3D1978

That is not a Nissan pressure plate, as far as I can tell. I haven't seen those four square blocks on a pressure plate before. Might be some sort of "performance" clutch. So somebody has been in there and it's worth checking their work. The spring fingers seem to have some odd unbalanced marks on them too. How does the throwout bearing look? Don't forget to check the pilot bushing in the end of the cranksaft also. And, since the transmission is out, change the seal in the front cover, and the tailshaft housing. Check the speedometer gear seals. All common leak points. Might as well do the shifter bushings, when you reinstall it. They get brittle and crumble after many years. p.s. you should probably do the engine's rear main seal also. They tend to leak. Painful to get everything back together and find out you should have done it. . .

Seems like a logical assumption. If it's a factory stock engine then a factory stock head gasket gets you back to factory stock specs. Trying to second-guess the engineers, who have all of the tools and money to test the variations, seems a bit foolish. Gasket restrictions are the same as port size restrictions as far as flow is concerned. You might have seen the comment from somebody in one of those old threads about the fact that after he got his cooling balanced across all six, using the head drilling/plumbing cooling mod, that instead of popping the seal on 5 or 6 from detonation, he popped all six at the same time. Something to consider. Probably better to spend time on the cooling system as a whole before fine-tuning the spread across the cylinders. Just an opinion.

Any L6 spray bar up to and including 1977 will fit. Looks like you could buy a junk cylinder head and save money if it comes with a spray bar. Don't forget the early 810's. Another option, if you can find all of the parts, would be a drilled camshaft. 1978 and later, including the ZX's. But you'd need the rocker arms and lash pads and it could still add up to a lot of money. Before you get too far you should probably inspect those dry cam lobes carefully for damage.

Look down the front cover area where the chain and sprocket are. The piece might have stuck on its way down. A magnet should be able to grab it if you can see it. I think that another way to fix that would be to braze it or use a high temperature solder. But an epoxy like SteelStick would probably work well too. You'll want to reinforce the joints that haven't failed yet also. It's a common problem with the early spray bars. Here's a whole long discussion about them on a different forum. https://www.classiczcars.com/forums/topic/41895-camshaft-oil-spray-bar-redesign-and-rebuild/#comment-377051

I don't think that it matters much. There's a small gap there anyway. I'd just file off any raised edges and put it back together. There will be plenty of good surface there. If you study how it works when everything is bolted together those two surfaces don't contact except under high loads. The locking pin in the casting and the inner sleeve of the bushings keeps everything centered. Under normal conditions the gap stays constant. p.s. for what it's worth, I have never heard of one those control arm (link) ears failing or the strut casting. The damage is certainly a stress riser but the parts are very robust. There are hundreds or thousands of damaged parts out there I'm sure. The stuck spindle pin problem has been happening for years.

Pasco? Odds are pretty good that you can get them out without cutting. A lug nut has the same thread pattern. Stick one on, spin the rod around a bunch to break up the rust and crud, and beat it back and forth with a hammer. It might come out. Also, a long 5/8" bolt works well as a drift to punch it through. Don't forget to remove the locking pin. I found on mine that the spindle pin was actually stuck in the bushing sleeve, not so much the casting. Something to be aware of. The rubber would let it move but then pull it right back in. Heat the rubber up to degrade it if that's the case. No need to catch it on fire, just enough heat to degrade it.

One fact that has been verified by many but might not be well-known is that the factory stock 280Z tank and fuel system suffers from fuel starvation on long left hand turns if the fuel level gets below about 1/3 full. You can find commentary about it in the various surge tank threads, I've had it happen to me a few times. It's a design flaw. It's pretty startling to have the engine cut out if you're accelerating through a wide long left on a busy street, on low fuel level. Something to consider for anyone rebuilding their fuel system or just looking to correct a real flaw in the system. A valid reason for a street car mod.

Are you racing or flexing? Ha ha....

Unnecessary opinion. Aren't you "flexing" with your performance knowledge? You can find threads out there about modifying tanks from other brands of car. You can also get replacement tanks, but they're expensive. It's one of those do-the-math situations. Good luck. https://s30.world/product/01-75-till-12-76-datsun-280z-fairlady-z-fuel-tank-vapor

The Airtex E8312 is a common aftermarket pump for the stock EFI system. It will put out 90 psi (unnecessary, too much) and about 30 gph (also more than needed). Don't get carried away on a bigger popular pump like the Walbro 255. 255 lph is 67 gph. Way too much flow and the pump will make a lot of noise trying to push through the small L28 fuel lines. There are several online calculators out there. https://www.google.com/search?q=horepower+fuel+pump+calculator You haven't described what you plan to do with the car. The race guys often use a swirl pot or surge tank.

It's the propeller (driveshaft) and pinion shaft flange. But, also, on the side axles, you'll need adapters for the 350Z diff. Probably knew that. The axles won't swap. The R200's long noses are inherently noisy. Just rough and sloppy ring and pinion cuts. Many people hear gear noise when their diff mounts wear out, front and/or mustache bar. Clunking during shifting is also a sign of worn mounts.

The viscous diffs apparently have a very slight hesitation before they grab. It's a racing consideration. Don't forget that your 75 has a unique bolt pattern and size at the diff flange. In case you find a different long-nose R200 to swap in. Mfactory has what looks like the simplest long-nose R200 LSD solution.

The RTz mount is for the long-nose. Great design, works really well. But it's too far forward for the short nose. There are/were several short nose mount designs out there but none are really striking as far as functionality. The front of the short nose is just in a bad spot. Empty space up to the thin sheet metal above it. An example, looks like what ArizonaZcar used to offer. Maybe they still do. Uses the control arm tubes as mounting points - https://technotoytuning.com/nissan/240z/z-power-cradle-short-nose-r200r230-and-ford-88 Many of the short nose options have been discontinued. Many of the early designs had problems. Too much leverage. p.s. I'm on CZCC too. Zed Head.

Maybe? https://www.google.com/search?q=fritz+cv+axles

There's a terminal block on the driver's side. Not the passenger's side. For the distributor wires. Should be red and green, or both blue if it's a rebuilt distributor.

The exhaust manifold is on the other side. How will you drive the turbo? Is this a real project? Something seems off...

Here's an old thread, food for thought.

Found one! https://www.ebay.com/itm/275788706682?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=xYdkasPjRAO&sssrc=2047675&ssuid=bBzFtXzvTQO&widget_ver=artemis&media=COPY The hole is only slightly ovalized.

A new MC has it attached. Motor Sport Auto has the pin. https://www.oreillyauto.com/shop/b/engines---transmissions/transmission---transaxle/clutch-parts/clutch-master-cylinder/0af50498271c/v/a/6637/automotive-car-1978-nissan-280z https://www.thezstore.com/isearch3?searchterm=clevis

That's a good idea, in principle, and you made it work. It would be interesting to hear the engine spinning with the ignition disabled, spark plugs in. To see how the starter handles those missing tooth ends. Hard to imagine that the tooth ends don't matter at all, but who knows.

It could just be that a valve guide was tight. People have had them pop off for no apparent reason. Usually after revving. The gasket should be reusable. I used the same gasket for many removals in the past. A 300 mile gasket should be fine. Beside the noise, it's a good idea to check valve lash on a new engine after it gets some miles on it. Beware though, today's camshafts have been known to flatten a lobe easily, soon after installation. It just happens. Hopefully it's not that but be ready. Post some pictures. Good luck.

Didn't listen to the video and don't know anything about the history of the vehicle but the simplest thing to do, if it's an L series engine, is to pop the valve cover and look around. They are known to throw a rocker arm occasionally, especially after sitting a long time. Sometimes a valve keeper too. More details about what you're working on will help.