Zed Head

Check the vacuum hose to the FPR for fuel. If it's original it's very old and the diaphragm can crack and leak fuel internally. It shoots straight in to the manifold. Also, your ECU is not likely to be 79 since that would be a ZX and they are wired differently. Unless somebody swapped in a 79 EFI harness also. A 79 ECU will plug in to 75-78 but won't work. I found that all ECU's from 75 through 78 would run my 76 with no problems. It's also known that bad ECU's often cause rich running. Broken solder joints seem to be the problem. But I'd check that FPR first. Also, have you measured fuel pressure? Welcome to "getting the old 280Z running right" world.

Found one! And just realized that I am obsessed with the notch and groove, I'm in all of the notch and groove threads. Looks like Nissan put the 1 on the right for position 1. So you're on position 1. https://www.classiczcars.com/forums/topic/49373-is-this-off-too-much/ Thread from which it came. https://www.classiczcars.com/forums/topic/56868-oe-camshaft-and-cam-gear-markings/

I've been looking at that Nissan drawing for years and I keep realizing that they put a lot of information in it, but it is still unclear. In the "Before" picture they show the number 1 on the right side and number 2 on the above left, on the perimeter of the sprocket. In the after picture the 2 is where the 1 used to be and 3 is on the left. But they don't clearly say if the before picture is the 2 position or the 1 position. It would make sense to have the position hole at the top. But they don't say. Anyway, based on the notch and groove your cam timing is correct and you should be fine. You're about halfway to needing an adjustment. It is odd though that your groove is below the perimeter of the sprocket base in that picture. Also interesting that there is apparently 16 degrees of play in your chain, since the groove did not move at all, but the damper did. Not sure what to make of that. So, there you go, much discussion but still wondering. Good luck! I'm going to browse around and see if I can find an original notch and groove picture with numbers. Maybe somebody has one?

p.s. 2 it looks like you think that the sprocket is already on #3. Can't tell because you wrote over the actual number! Anyway, The other first thing I might do is to just set the damper at TDC/zero, remove the sprocket and replace it at a position that looks right. Use a chain holder tool. You can make your own out of wood.

Looks like a PO adjusted the sprocket already to position 2 or 3. If you put the timing mark on zero (TDC) (like you're supposed to) the notch will be after the groove. Like "after adjustment" in the FSM. It wouldn't be from chain stretch on position 1 because that would delay the camshaft mark (before adjustment). Make sure also that the tight side of the chain is tight. The left/driver's side. Another possibility is that your damper is starting to fail and the timng mark has moved. And, that looks like 16 degrees, not 12. If it was mine I'd remove the #1 plug and try to confirm that the piston is at TDC. Then see where the marks are, and see if you are on position 1, 2, or 3. You might be able to see the tensioner also to see if it is pushed out. p.s. it's a chain. Good luck.

Might find something here - https://bringatrailer.com/search/?s=1970+240z

Weird how complex the whole fuel filter market is. Few details and what looks like poor conversion skills. 10 mm = 3/8"...not. Here's a couple from the local store, one with paper media, one with bronze. One about 4" long, the other undefined. One special order, the other available. https://www.oreillyauto.com/detail/c/spectre-performance/spectre-performance-fuel-filter/spt0/5965?q=Spectre+Performance+Fuel+Filter+-+5965&pos=0 https://www.oreillyauto.com/detail/c/trans-dapt/performance/filtration/fuel-filters--universal-/383bc52af696/trans-dapt-3-8-inch-inlet-3-8-inch-outlet-fuel-filter/tdp0/9177?pos=3

They're cheap too. Main problem is the 8 mm (5/16") nipples. https://www.rockauto.com/en/catalog/nissan,1978,280z,2.8l+l6,1209260,fuel+&+air,fuel+filter,6200

Don't overlook that the pressure drop is affected by the area of the filter media. Not just the pore size. So, a larger diameter filter will be less noisy. It would be interesting to try one of the big 280Z EFI filters as a pre-filter. There's a reason there so big. Lots of surface area in the pleated media. Also, if you're filtering to save the pump don't over-filter. The clearance inside the vane-type roller pumps is pretty big. Certainly greater than 20 microns.

You need to add more detail. When, and exactly where? There are three "lugs". Actually two lugs and a spade. SteveJ is asking about the spade (black and yellow wire). With the key at Start. The 12 is a good sign though.

Slide hammer is not a bad idea, but good look finding that thread pitch. I have vague memories of using a rag and a pair of vise-grips, with a hammer tapping sideways on the pliers. Or maybe a big screwdrive levering on it. Anyway they do get stuck. Nothing special in there. I found a new Z store. TotalZPartsDatsun 240Z 260Z 280Z 280ZX 300ZX Speedometer Pinion Gear...NOS (new old stock) speedometer pinion gear full assembly, including the sleeve, seals, and the retaining pin. It has a 17-teeth gear & measures about 3 1/16" in total length. 18, 19, & 20 teeth ge...

Are you sure? The diagram shows a left side and a right side, from the Hazard switch. It's a 78, I didn't look at any other diagrams. The Hazard switch is basically a gate between power and the flasher, and the lights. Since the flasher comes in to play the short to power has to include the flasher circuit. Basically it's just completing the circuit, like a short across contacts inside the switch. Interesting problem. For what it's worth, I erased about three different paragraphs about this problem. Writing about it does help the brain work...

$137,000. Kind of amusing that the bulk of the discussion on BaT was about AC and undercoating. Bring a TrailerVintage Restoration Program 1972 Datsun 240Z 4-SpeedBid for the chance to own a Vintage Restoration Program 1972 Datsun 240Z 4-Speed at auction with Bring a Trailer, the home of the best vintage and classic cars online. Lot #199,214.

That cam doesn't look very aggressive. Not like a typical rumpety-rump muscle car V8 cam. Probably won't cause a problem. I've seen belt-driven vacuum pumps. You could probably add one after the fact if you find that you need it. Looks like you can get electric also. https://www.summitracing.com/search/part-type/vacuum-pumps-street

On second thought it might be the Hazard switch. Lots of mysteriousness in there. It has power when the key is off. @SteveJ seems to feel comfortable with it. "even when car is off"