Zed Head

Datsun Parts and Accessories sounds like Datsun Parts LLC. Are they based in California? Post some screenshots for people who don't do Facebook. Can't see nothin' unless you join the private group. What's the point of Private if you're trying to sell parts? Makes no sense. Sketchy.

If swapping regulators worked I'd say you had a bad gauge and/or the adjustable regulator was plumbed incorrectly. 40 psi should have worked "okay", maybe even just right. Many people measure 40 psi on their stock regulators. It's higher than spec. but the old EFI systems tend to run lean. Sorry to be a buzzkill. It worked, apparently, but it's not clear why.

I'd make a plan and do the simple stuff first.

The fact that it starts implies that the wire back to the coil is correct as CO says. The tachometer, ECU, and ignition module are all on the same circuit. The fact that it runs best with the throttle wide open kind of implies that it might be super rich. That could be from a hole in the fuel pressure regulator diaphragm or if the coolant temperature senosr circuit is open/high resistance. You might do the Pin 13 resistance measuremnet at the ECU and see if it's in the right range. And pull the vacuum hose to the FPR to look for fuel. It should be dry. p.s. you can test the injectors using a jumper wire from the coil negative terminal. Attach a jumper, turn the ley on, and tap the wire quickly to ground repeatedly. Every third tap should "click" all of the injectors. Don't do too many "clicks", each one squirts fuel in to the intake system. This will test the wiring and the ECU function. It's pretty east and you don't have to listne over starter moise. Of course, you can also use Noid lights in an injector connection too. The factory way. But, hopefully not the case, you migth also have a bad ECU. They run rich as they start to die.

I think this low miles 76 might have slipped by when nobody was looking. $67,000. https://bringatrailer.com/listing/1976-datsun-280z-88/

I think I found a picture

A followup - The water temperature switch is in the thernostat housing. There's a wire to an eyelet that is supposed to attach to a mounting screw for grunding. The wire often breaks right at the junction with the switch body. The vaccum solenoid would be mounted somewhere near the front of the engine above the intake runners of the first two cylinders. Notice that the black wire is a separate wire with a bullet connector and an eyelet, to connect to a screw for ground. Easy to lose, it's just a short little wire.

Can't you just use washers or shims (fender shims can be swapped with the bolts in place) as spacers and try them in different spots until things fit right? Then take the measurement and get the right spacer in the right spot? Even after T3 tells you something you still won't really know until you try it. https://www.harborfreight.com/144-piece-body-shim-assortment-67585.html

The vacuum switch might be for top gear timing advance. It opens vacuum to the vacuum advance canister on the distributor in high gear. Retarded ignition timing is cleaner than advanced. It's an emissions thing, some people remove it. The water temp switch is also emissions related. It switches to the more advanced timing pickup in the distributor when the engine gets warm. If you don't have the dual pickup distributor it doesn't matter. I think that cars with catalytic converters might not have either of those, CA vs Federal. I had both. Too many pages to go through and figure out what exactly your collection of parts is. But you don't really need either of those things, by the labels you gave them. Just make sure that any loose wire ends aren't powered and/or are protected. . .

And if you click on the Fees link, it's dead. Edit - actually it's half-dead. You have to scroll down there yourself. But still nothing about withdrawing or changing your mind or penalties if you renege on the final sale. https://bringatrailer.com/how-bat-works/#seller-fees How Our Fees Work Sellers pay a $99 listing fee, with the option to add our Plus photo service for an additional $330. There are no other seller fees on BaT. Buyers pay a 5% fee on top of the final sale price to BaT, with a minimum of $250, and capped at $7,500. Contact us for pricing of our White Glove Service.

I looked around on BaT's web site but couldn't find a copy of the Seller's agreement. They should just post the full document on the site so everybody can see how things work. I assume that it shows up after they get all of your information. It's hidden to everyone else, apparently. Edit - I filled out the first page then hit Next. It just took me to another page that wanted even more info. You have to get all the way through before you know what the terms are. A pain. Follow the trail - https://bringatrailer.com/resources/submitting-on-bring-a-trailer/ https://bringatrailer.com/submit-a-vehicle/ https://bringatrailer.com/account/listings/new/?processing=0&tab=1

This is all "after the fact" detective work. I don't think that crshowers saw the inside of the engine before it was buttoned up. The stuff on the bottom of the oil pan might tell more than the stuff on the piece of foam filter. SteveJ's forbidden glitter would be there. . .

A coin in the picture would give a size reference. Magnified or not. Might just be old shavings from before. You might check your oil pickup tube screen also. If you haven't already. And, if you're still worried check the oil pump for damage. If there's stuff in the filter it passed through the pump.

Interesting recent sale/no sale on BaT. I've not seen the contract or agreement that I assume sellers must agree to. Does anybody know how a Reserve price is set? https://bringatrailer.com/listing/1973-datsun-240z-264/#comments-anchor

Not super clear what's happening. How about a softball in the cargo box behind the passemger seat? You mentioned the diff, you could swap stub axles. You didn't mention the hub flanges. Might have a bent hub axle. Or, maybe it just sounds like the rear but is actually from the front.

All of the 280Z's came with a 3.54 R200. Swapping to a 3.9 will give better pickup in 1st and more time in overdrive.

Thanks. I found the one reference to reverse. Doesn't look like the guy actually had the pop-out-of-gear problem though. Yours is the first I've seen describing reverse. If your fix fixed it, great. Your post was a surprise. Carry on.

Not sure what, exactly, "Reproduction" means but there's this - https://jdm-car-parts.com/products/reproduction-mk63-front-brake-caliper-for-skyline-hakosuka-kenmeri Here's more - https://www.jdmjunkies.ch/wordpress/2015-12-11/240z-the-super-rare-sumitomo-mk63-ex-works-brake-delivery/ And this - https://www.jdmjunkies.ch/wordpress/2021-01-17/240z-the-guide-to-sumitomo-mk63-brakes/

I was going to also ask if they had any inherent value. They might, to the right person, since they're probably NLA now. Don't turn them in as cores. For what you're doing Id guess that performance will be about the same between the two options. You're planning to autocross it, right? Are you using the vented rotors?

That's odd. I've not heard or read of anybody having a reverse problem due to the shifter.

Any ideas on how they would end up on a 1974 260Z? Question for anybody. Strange...

I'd swap the wheels first. Easiest and a possibility.

I'd take a good close look at how well what you have fits together. It has the signs of hack. You might find that you need to start over to make it right.

p.s. since you only have two bad cylinders it might be worth the time to just replace valve seals on those two. If it was mine I'd probably just do the two intake valves. Why mess with the others that appear to be just fine?

You'll have to look very carefully through the valve spring. Bright light, magnifying glass, or camera with close-up shot. Here's a shot of an exposed one and link to the guy's video. No idea who it is, found it by Google.