Zed Head

It gets weirder. 1970. 5/8". 0.625". Matching master and operator.

Looking further I think that you asked a good question. I'd never really thought of it before, and even now assumed that you would just want to match the master and slave bore sizes, that they would be the same. But that is not the case, see specs below for 1976. Add on to that that the 240Z's had a taller pressure plate and maybe it is important to match the specs on all of those components. Pressure plate, master, and slave. Many people put later model pressure plates on their L24's. It deserves some study. Notice that image I pasted above has the 1976 style slave cylinder non-adjustable rod. Not the same! -

Actually, there is some weirdness out there. 3/4" does not equal 0.690". Not sure if the 3/4 molded in to the cylinder is its size or something else.

The seller didn't say, and nobody asked. Probably works just fine. He didn't get his price. He was hoping for 20, only bid up to $13,750.

11/16" = 0.6875 inches = 17.5 mm. I think that that's all that's out there. The self-adjusting slave cylinders have a spring inside. No need for the external spring. Nissan improved the system. Maybe a PO already used a newer cylinder. You'll need to swap rods like site said though, unless you change the clutch fork. https://www.rockauto.com/en/catalog/nissan,1971,240z,2.4l+l6,1209158,transmission-manual,clutch+slave+cylinder,2044 p.s. if you put your car info in the signature box and save it it will show up under each of your posts. It's under Account Settings. https://www.classiczcars.com/settings/signature/

Here's an interesting 75. Has had the EFI system swapped for a 1983 system. I wonder if it works well without an O2 sensor. Maybe @cgsheen1 knows. Looks like they did all of the parts, from AFM to ECU to ignition module/distributor. I'd comment on BAT but don't want to mess with the auction. https://bringatrailer.com/listing/1975-datsun-280z-66/

Automatics kill (value). $5,000 for a running, driving, passed-emissions-in-CA 280Z. https://bringatrailer.com/listing/1978-datsun-280z-193/

No reserve 240Z project with Stromberg carbs. Non-running for 20 years. Oak Harbor, Washington. @Terrapin Z https://bringatrailer.com/listing/1973-datsun-240z-313/

Loose mustache bar diff nuts is not an uncommon cause of a clunk.

I hate to say it but I don't think that you can trust most aftermarket parts today. Everybody is buying from Asia and they probably don't want to get tied to a specification. The primary spec. on the only part that had a spec. was huge. It was 1978 when Nissan created their 0.84 - 1.02 spec. About a 17% range. The Wells coil today, above, is 0.7 - 1.4. 50%. Not even close to the Nissan spec but they're selling it as a replacement. https://www.made-in-china.com/quality-china-product/ignition_coil-4.html Four E's VietnamFour E's VietnamDecade-long expertise in manufacturing premium Aftermarket Ignition Coils

I think it's just where the internet is going. I did go to the NGKSparkPlugs site and look and nothing came up. I also searched for a coil for my truck and it did come up. The database for 1978 280Z was just empty. There's probably an old NGK catalog in the back of somebody's parts store that has the listing. We might have to go back to paper. https://ngksparkplugs.com/en/part-finder But wait! I tried NGK.com (which oddly says that it is not associated with NGK Spark Plugs...so confusing.) and found it. But..it's Not Available. From them anyway. Watch out for counterfeits. Okay, I'll stop now. https://www.ngk.com/application/search

In case anyone is wondering - Here's 1976 - Here's 1978 -

Bollocks!

Nope, now it's a Reddit post - https://www.reddit.com/r/Datsun/comments/1atbwl8/do_i_have_the_wrong_ignition_coil/

BUT. Now it's back, halfway, but with a +2. I wonder is CZCC is one of the +2. Searching... -

Found another example of the sad state of the AI "boom". The AI overview uses two single word references to write two full paragraphs, from one single Ratsun thread. BUT, even scarier, as soon as I copied that Ratsun link in to my other post AI stopped using it. I think that AI is watching posts in real time and adjusting replies. https://www.google.com/search?q=ngk+U1099 Before - After. It's gone. No more Ratsun reference -

The number does look familiar. But, unfortunately, when you search it, not much shows up. It's something that I've noticed recently, that many of the old sources that I was sure are out there on the web, seem to be missing. I think it might have something to do with the monetizing of the internet. On top of that, the genius AI chatbots and their "overviews" cite posts from Reddit or forums like Ratsun as authoritative references. They just steal from the single source and post it as their own creation. The internet is getting really weird. https://www.google.com/search?q=ngk+U1099 https://ratsun.net/topic/83046-1977-620-l20b-no-spark-condition-on-fuel-injection-conversion/

How do you know it's the correct coil? RockAuto doesn't show it as a choice. https://www.rockauto.com/en/catalog/nissan,1978,280z,2.8l+l6,1209260,ignition,ignition+coil,7060

Actually, some specs are there, I missed them. Pretty wide range. Looks like RockAuto is confused though on the ballast reistor. They list one for use with the "external resistor" even though, as CO pointed out, 1978 doesn't use it. It has the module with current limiting capability. I'd just go down to Oreilly Auto with my meter and see what they're selling. (Edit - actually I'd probably just go to the wrecking yard with my meter. Coils are spendy at the parts stores!) https://www.rockauto.com/en/moreinfo.php?pk=940830&cc=1209260&pt=7060&jsn=448 (what's a 200 scale?)

Rockauto has a selection of coils. Probably meet spec. although they don't show them. You might start planning for the ignition module to fail though. It's what they do.

How about the voltage regulator? It has moving points that could get stuck. Maybe it's backfeeding in to the ignition system. The brake light in the dash should light when the key is on, engine not running, but go off when the engine is running. I think that that is also controlled through the VR. Should start and run with it unplugged. Maybe you'll get lucky. Edit - actually I'm not sure what it will do if you unplug it. Have to study the wiring diagram. If you have a spare it might be worthwhile to swap it.

Maybe the reference to 1979 and 80's got the thinking off-track? I see 280z. Blue had a ZX transmission though, in his writeup. Maybe even bent the shifter, it looks bluish at the base. Anyway, he's got plenty to think about now.

The 280ZX shifter has a rectangular hole, those bushings won't fit a Z shifter. Not clear why he'd get one of those if he got a 280Z transmission. The ZX shifter looks a bit stout for bending also. Who knows!? 🤔 I found this old posting from Blue. https://atlanticz.ca/zclub/techtips/shifterbushing/index.html

Be prepared to lose the circlip that holds the clevis that has the two bushings on it. Be very careful. It will be slippery and fly far. And don't just eyeball the shifter bushings from the top. The bushing on the bottom can fail also. You'll want to pull it all the way out and have a look. Many, maybe all, of the parts are still available from Nissan. You might just stop by your local Nissan dealer and get a full set of bushings, clevis pin, and clip to be prepared. That's what I'd do. https://www.carpartsmanual.com/datsun/Z-1969-1978/power-train/transmission-control/5-speed Datsun Z Transmission Control Lever & Fork (5 Speed-FS5W7...

I bought a rebuilt AFM from MotorSport Auto and found that it was too rich at idle to pass emissions. I could open the bypass up all the way and it was still too rich. I had to reinstall an old used one that came on a 78 parts car. Something to be aware of. That was in 2009. No idea what today's rebult AFMs are like.