Zed Head

It can still be difficult if you have a dash cap. The cap holes are barely big enough. The 260Z and 280Z tachs are voltage driven. They'd work but you'd need to rewire them with a wire from the negative post of the coil. Probably with the 2.2 kohm resistor. And you'd need to connect the power wires when you remove the 240Z tach since igntion power runs through it. Not a big deal really. And, the fonts are different. A new thought - it might also be that the matchbox module is failing. Is it Nissan original or aftermarket? You could wire in a GM HEI module as an experiemnt for about $30. Always good to have a backup anyway.

If it was mine I'd reach up and wiggle that wire around while the engine is running. If something changes you'll know there's a possibility. I might even attach some extraneous metal to the post that the wire encircles. I don't know what exactly happens as current pulses through that small coil of wire but I imagine that it generates a field in that core that passes in to the body of the tach. Then magic happens.

Move the lathe to the car. On-car-rotor turning is a thing. And who checks their new rotors for runout? That's not obvious either! What's going on here!

I can't remember the exact details but I know that people have fiffled with the loop of wire on the back of the tach and had good rresults. I think that they might have removed a loop or made it bigger. It generates an electromagnetic feild and the electronic igntion boxes apparently overload the current sensing system. They pass more amps. As I understood what I had read and barely remember. I think that you can reach it from underneath without removing the tach. https://www.ebay.com/itm/235464345938?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=sQc_o1-rRnS&sssrc=2047675&ssuid=&widget_ver=artemis&media=COPY

Here's what the matchbox expects. Don't know if it will help the tach. From the 1982 FSM.

What is being investigated? It's not obvious.

1972 electronics technology and parts inside these current sensing devices. I found this interesting page on the internet. Might have something for the guys with electronics expertise. Seems like a tachometer rebuild might be in order. The page is a good example of how wrong things can get when a person tries to be clever with page color and font. Easier to read if you highlight the text with your cursor. Not sure of the quality of the information but it's an example. https://www.sw-em.com/Smith's Tachometer.htm

The collector/investor car market is a strange place. https://bringatrailer.com/listing/2010-honda-element-22/

In the States they just stuck on the finned cover and called it good. The 300ZX's got them with the LSD diffs, CLSD for sure and I think the 88 Shiro VLSD. Only 87-89 I believe. The FSM shows maintenance procedures on the CLSD's but no pictures of the cover. It's one of those things to look for for those trying to get limited slip for their early Z's. Like finding gold in the wrecking yard. Here's a typical finned cover. https://bringatrailer.com/listing/1988-nissan-300zx-43/ But this one looks like it might have the plumbing for fluid cooling. Different cover. First time I've seen it. Interesting. https://bringatrailer.com/listing/1989-nissan-fairlady-z-2/

@Mike Edit - but now it has come back. Strange stuff. Probably uncipherable. This thread has disappeared from the Activity page. It should be one of the top ones since I posted three hours ago. But I can get to it through the Notifications links. Weird. Here's the latest on the Activity page. CO's five hour old post is top of the page.

That's pretty "cool"! Can you take a picture of the page and post it? I assume that it's in English?

Cooling fins are on the CLSD R200's. The open R200's just have the plain covers.

Isn't the ring gear located by an interference fit on the center of the carrier? There shouldn't be any play to play with.

I had the feeling I was missing something obvious. 😟 I had assumed that the purpose of the notch and groove was known. Didn't read the accompanying words. I did get things right on my last suggestion to reset the mark on zero/TDC and see where the notch and groove were.

I think that your cam timing might be off by a tooth. If you're careful you can get it right without removing the front cover. You'll need a chain holding tool. Not sure how it would get off a tooth except for previous misassembly or radical chain wear. Also, I think that you can get a really close estimate of TDC using the damper key keyway in the crankshaft. The keyway should be aligned with the top of the block. Since you have the damper off it should be doable. Don't forget that the engine is tilted so up and down are askew. All timing events are relative to the crankshaft and its pistons.

It was fun looking around at the different dampers out there on the internet. Seems like your damper is fine. I'd rotate the engine around twice by hand and put that bottom/left side mark on the pointer. Then see how the cam sprocket lines up. If you use the cam sprocket to turn the engine make sure that you turn it backward before checking your marks. So that the slack is removed from the tight side of the chain. That might explain some of the discrepancy in your notch and groove. Ideally, everything is assembled and the engine is turned clockwise via the crankshaft bolt, or the fan belt, looking at it from the front, to keep the tight side of the chain tight. Assume that the TDC/zero mark is the farthest to the left, looking from the front.

I found another that doesn't say Euro. It looks about the same. Not sure what's going on here. I'd probably take the time to verify TDC and mark it on the damper pulley. Then use a dial-back light to set timing. https://maseraticompound.com/products/datsun-240z-main-crank-shaft-pulley-with-extra-ac-belt-pulley

I found an ad for a "Euro" damper and it looks like yours. Don't know how it's different from State-side. I'll look a little more. https://datnissparts.com/x-euro-crankshaft-damper-pulley-harmonic-balancer-240z-260z-280z-510-all-l-engines-12303-e4100/ Spun the picture in Paint 3D. Yours

If you show the offers it could be an auction site. I offered $1.67.

If that's the notch it does look like you have problems. Rotating it to get it aligned would make your damper marks even farther off the pointer. Looks like a bad damper. How about a picture of the face of it? That second pulley has seen some weather. Looks very old. Don't be afraid to really give it a tug to try to pull it apart. It's supposed to be very firmly bound.

That does sound like the 280Z strut. The strut towers in the body of the 280Z are taller than the 240Z's. I've never heard of anyone doing that swap, seems like there would be very little suspension travel and the springs would be designed for more wight. The back end would be higher. If you look closer you might find more modifications. Cut springs maybe. The shocks might be fully compressed already. I'd guess that you'd be better off resintalling the 240Z suspension. Here's a link to the parts page. Not much interchange. p.s. you can tell an R200 from an R180 by the rectangular block of metal under the drain plug on the cover. https://www.carpartsmanual.com/datsun/Z-1969-1978/axle/rear-suspension Borrowed this from a recent BaT listing.

The blue wire from the coil (-) terminal supplies the tachometer with the voltage signal. You can leave it connected at the coil, but disconnected at the old igniton module. It's on a branched circuit. You can follow it out on the wiring diagram and see it.

If money is not a consideration pick the one that looks like the most fun. Better check parts and procedure availablity though. An engine swap would actually be the "fastest" way to get back on the road. Machining and assembly time on the existing engine is going to add up. Good luck.

Piston stops in the plug holes. Rotate backward and forward and mark each spot. TDC is halfway between. Moght as well check the notch and groove. Put the groove over the notch and that should be within a few degrees of TDC. Your cam sprocket seems off in the picture. https://www.oreillyauto.com/detail/c/comp-cams/comp-cams-piston-top-dead-center-locator-tool/com0/4795

Not clear what happened or what you're asking about. Where is the bolt and washer that holds the damper? Did you just grab the damper and slide it off by hand? Where is the woodruff key?