Zed Head

Turbo engines have lower CR's. And gauges vary. It's the comparison of all six cylinders that really matters.

#6 looks wet and like it has not been firing much. The strap should be grayish-white like #5. Does it smell like gasoline? Something is not quite right.

My two main paths to any web site both worked fine. Google and typing in the name in the address bar then using CTRL-Enter to bring it up. You're back!

EuroDat put a paper together and has posted a lot about rebuilding. The parts are generally available. I think that you can get them cheaper than at ZCD if you search around. Seems like there are one or two sets of parts that everybody resells. There might be extra parts in a kit or a couple of missing parts, but the bearings and seals in the kits seem to be of good quality. The synchros can be questionable. Have you found any metal on the drain plug magnet?

Does injector #6 work with the cap up? Can't tell if you're saying that you got boost and up to 70 on 5 cylinders or something else. How does spark plug #6 look after boosting to 70 mph?

Might as well tie things together. A plan will form eventually. Keep original engine (block) and get more power seems to the heart of it. I saw "save money" somewhere also. Moderate budget power increase seems like the goal. I would avoid using words like drop or slap or toss when thinking about modifying your engine. People write like that often but only the pros can really do any dropping swapping or tossing of parts in engine work. Even just removing the crankshaft and honing the cylinders, then using new rings on the pistons and bearings on the crankshaft, is a complex operation for the average weekend mechanic. You're not going to drop in a new crankshaft, swap some pistons, and toss the engine back in without spending lots of money and time. https://forums.hybridz.org/topic/131952-ld28-crank-stroker-market-rate/?tab=comments#comment-1224639

Your ID looks right. It also has the dust/dirt shield over the slip yoke area. Which gear does it pop out of? There's quite a bit about shift lever interference causing 5th gear to pop out or not engage completely. Blown up bearings are common also.

If you have the old injector and a 9 volt battery you can jump the terminals and it will click if the solenoid and spring are working. You can use a 12 volt battery also but it makes some people nervous. Just tap the terminals, don't leave it connected.

Lots of good stuff in the FSM. Like the injector coil resistance, 2-3 ohms, and the injector opening description.

The light test is one way to see if the electrical connection is working. Many ways. Screwdriver on ear and injector, stethoscope, colortune, ...

Good luck.

No, the 2.5 ohms is across the injector terminals, on the injector. I copied the other part over just to show that it was for the turbo's ECCS, not the NA system. All of the injectors, NA and turbo, measure about 2.5 ohms. Good luck.

Yes, the spring inside the seal. It can leave a groove on the slip yoke surface because the slip yoke doesn't slip much on the Z's, because of the IRS. Just a possibility for your leak. There are other leak areas. What was the "chunk" you found at the tail area when you took the seal out? There's a bushing there that the slip yoke rides in. If it's broken your slip yoke will wobble around. Didn't mean to jump in front of you EuroDat. @EuroDat You should be sleeping by now, unless you're watching USA election results.

Your injectors are about 2.5 ohms resistance, not 16. Make sure you're getting a good measurement. Your picture of #6 looks like a wet plug that was getting fuel but no spark.

Check the surface of the slip yoke also. If the seal wears out too far the metal spring inside will wear a groove in the slip yoke. Metal shavings are not always a sign that rebuilding is needed. Fine shavings are normal. The blacked out text is odd.

What is the gap on those plugs? Dave suggested that you're not getting spark on #6, not that the injector was bad. No resistance on your injector would mean that it's not going to open. But it's hard to see how you could get a perfect idle on 5 cylinders. There's no clear path to follow, just a bunch of odd things going on, that don't really fit to define a problem. Did you already replace injector #6 once, see below? If so, did you get a turbo injector? Another random bit...

Seems like a good idea except for the pressure concern. I wonder if a person could plumb in an electric pump and just circulate oil from the sump/pan. Of course, the oil will only be cooled to the coolant temperature level. I think it gets their anyway as it travels through the pump, block and oil filter. Oil coolers really seem more like extensions of coolant coolers. The oil should equilibrate to the temperature of the metal it passes by which is equilibrating to the coolant temperature. Where would a person place the oil temperature sensor? In the pan/sump? How do you know what a proper temperature is? When does it need extra cooling?

Setting up your sale to end on Election Day probably doesn't help but here's another Z that didn't meet reserve, the 39,000 mile green 76. And, another Z, a 75, just went up. https://bringatrailer.com/listing/1976-datsun-280z-38/ https://bringatrailer.com/listing/1975-datsun-280z-26/

Seems like you're trying to work on several problems at the same time but some of them are caused by one main source. If you fix the main source the other problems you're working on might go away. Trying to fix the secondary problems might actually create new problems, once the main source is removed. Seems like there's been some distraction.

They look Abby Normal.

Make sure you check the other odd things like the main wire from the coil to the distributor cap. Things that move when you raise the cap. Seems like there's a lot of crusty stuff floating around in there. The spark can jump anywhere along the path on top of the rotor. When you raise the cap you move the rotor away from places to jump to. I might try a piece of electrical tape on top of the metal as an insulator, just for an easy test. Overall though, a simple tune-up with new parts might be the way to go. The old pocket knife electrode scraping might not be good enough.

Might be carbon tracking. With the cap up it breaks the path to ground.

Have you had it apart? It's 38 years old. Check that the rotor head is firmly seated. Look at the top of the inside of the cap for wear marks. Make sure the shaft is tight and the disc spins smoothly. Maybe the cover is causing misalignment of the shaft.

I'd rather work through the cover. It's just an idea, no need to spend so much effort shooting it down. If you have one, take a picture and show how much room isn't there. I'd think the only people who really know what it looks like are those who've forgotten to put the plate on. If you have the parts, a picture will make the case.

Just get it running and drive it. It's an old beat-up 240Z now and it will be an old beat-up 240Z after you have some fun in it. Get good insurance before hitting the road. That will be the only money you should really spend on it. That's what insurance is for, reducing risk.