Zed Head

There's a "Related Item". https://www.thezstore.com/product/5031/parking-light-upgrade-harness-70-73-240z

Wouldn't be a surprise if an aftermarket part was made incorrectly. Get an OReilly part and see if it's better. Take the Duralast part back if Oreilly works. Beck Arnley is almost certain to fit correctly. But, wow, prices have gone up. https://www.oreillyauto.com/shop/b/lighting---electrical/sensors/engine---drivetrain-sensors/oil-pressure-sensor-switch/9a4df8f34742/v/a/6637/automotive-car-1978-nissan-280z?q=oil+pressure+sensor%2Fswitch

He had a thread about the car. He did the math on selling it for parts and chose a price for the whole car. I think that eBay is the wrong place for the car though. That's a local market car and Craigslist or Facebook Marketplace are better for local markets I think.

The W on the module is from GM's labeling. Might be that GM used a white wire. In your writing above I thought that you were referring to the GM HEI module not the Nissan module. Didn't realize you were deep in to the circuit board of the Nissan module, looking at those wires. Most people just use the diagram or the labels on the wire clamp. Don't know anything about the other person, but the basic test to see if the wires are connected correctly is to watch your timing light mark afterward. If it jumps around it's probably backward. If they're backward it won't hurt anything you just swap them. There's an accurate edge of the variable reluctor signal and a fuzzy edge. @Captain Obvious has some old comments about that.

Everything is discussed in that first link I posted in #3. The turn signal contacts get gummed up too. Pictures of the switch internals would be much much better than dirty q-tips. What's up with that? I sure hope I don't start getting those e *a^ %r$ w#a&x ads again.

Actually, in his drawing he does show the G and the W labels on the module. You have to follow the green wire all the way to the module pin. All of the modules have letter labels on the pins. That has been my way to remember, the G on the module attaches to Green from the harness. That leaves W for the red wire. You seem to have it backward. By the way, maybe you didn't notice but the red wire clamps on your original module have labels also. G, R, L, BW, BW, B. L = blue.

Might be why he decided to switch to a GM HEI. Looks like his was wired backward somewhere along its journeys. The FSM's all show Green on the outside. Here's EuroDat's - Here's 75 and 77 -

It's in that thread I linked above. I made somebody angry with my naked hostility.

It is normal for pipe threads to get tight after a few turns. The hole is tapered, it's how they work. The seal is created by the male end getting jammed in to the hole. "A few turns" would be a few threads, so it sounds like it's fine. You might be overthinking things. You'll probably need sealant though if you try to use one of those adapters. Because the seal is created when the pipe gets hard to turn you usually don't get to decide when you're done. You crank it down and get what you get. A good sealant gives you some adjustability. This stuff works well, you can get it at Home Depot. https://rectorseal.com/rectorseal-no-5-group/ Application Chart

I've posted about this before...many people use the GM HEI module in place of the "Ignitor"/power transistor on the 280ZX ECCS systems. Which should be a 5 volt square wave. I've wondered why it works when, in theory, the HEI module triggers on the switch from negative voltage to positive (maybe vise-versa, can't remember). Just one of those things I've wondered about. I had a theory about transistors but don't have the knowledge to rationalize it in words. But, in short, it might work even though it's not designed for it.

You could check the switch for shorts to ground or shorts to other circuits. If it checks out then the very small amperage of the relays probably won't bother it. You can also check the downstream circuits for shorts also. Which relay kits did you get? Both the headlight circuits and the running lights can overheat.

That Facebook link brings up a blank page. Doesn't even ask for a log-in. What's a "commerce/listing"? Shouldn't it be on Facebook Marketplace?

Here's another that shows the little pieces. Don't lose them.

Here's one that covers much more than the headlight switch. Pic 37 is about the starting point. About 2/3 down the page.

Carefully bend the four metal tabs back and the contact board will lift out of the case. Be very careful, there are small springs and things inside. You'll probably find pitting and maybe something melted. If you can get things cleaned up and use relays it should be fine, with the lower current. Be careful with the wires and solder joints. After many heat cycles they get brittle and often crack and break off. It's a pain resoldering them. Looks like somebody might have been in there already. There a threads about working on the combination switch I'll post one up if I find it.

@Terrapin Z might have a set.

Here's another. I thought it might be an investment flip but there seem to be other reasons. Kind of humorous. https://bringatrailer.com/listing/1970-datsun-240z-108/ https://bringatrailer.com/member/2shots/

Very nice 1971 No Reserve. https://bringatrailer.com/listing/1971-datsun-240z-271/

Overall, the whole thing was kind of odd. He said that he's been visiting the Guild showroom for years. Wouldn't give the name of the builder on the open forum but said he knew who it was and would supply it to serious bidders. But then later in the posts said he had a vague memory, like he wasn't sure, that the guy's name was Larry. But then said he had contacted the builder about the parts on the car, so he must have known him pretty well. Almost like the three of them were teaming up to sell the car. Very strange. I saw some odd stuff on the bottom of the car. It was painted black up to about the ends of the floor pans. The welds there look odd compared to other unmolested cars. The door jamb tag is a reproduction. There are two different firewall VIN stamp pictures in the listing. Edit again. I'm spending too much time on the internet. Anyway, I had wondered about this. Why stop painting there and why do the welds look so chunky. Here's a comparison. https://bringatrailer.com/listing/1972-datsun-240z-289/

Here's something different. Only $7,700! https://www.ebay.com/itm/325776092449

Seems like he might have paid for the looks and now he's finding out what's underneath as he tries to move it on. Funny that he says he spent years trying to buy it but knows so little about it. Wonder where it will end up next.

That's a first. Should be an interesting project. The cam towers have a lot of mystery attached. Nissan says that if they're bad the whole head needs replacing. You probably have read that. Then, of course, there's the "tap the towers while spinning the cam" adjustment method if they're removed. Haven't seen towers from a different head tried. Seems like it should be possible, if the cam spins freely what could go wrong. Too bad they don't have "tower saver" journal inserts. Maybe you could make some.

The comments continue on that red G Nose 72 even though the auction ended yesterday. Apparently it's meant to be a show car, as The Guild guy inferred earlier. I copied the image before it gets removed as "non-constructive". Kind of feel bad for picking on the guy's car but he doesn't want to let things fade. He's asking over $40,000 for it, so he can't expect no questions asked. What does $40,000 get you? What he should do at this point is put that paper trail together, documentation of it's provenance to remove the mystery, and put it back on the market in the right way. $40,000 is a risk unless you have money to burn. Drama!

You might turn the head upside down and fill the passage with oil to see if it's leaking from the cam journals like you mentioned earlier. Or some lighter fluid like kerosene/diesel/heating oil. That was a thought that seems on target. You could also just blow compressed air in and see what happens.

If you click Images here a bunch comes up. It's a hot topic! https://www.google.com/search?q=coolant+temperature+sensors+curves