Zed Head

The engine sounds kind of "cammy". Confirming cam timing and ignition timing will help. I wonder if your damper is bad. Your ignition timing might not be where you think it is. Feels like this has been discussed, not sure. Make sure that you pull the straight side of the timing chain tight when you set the timing mark on the damper to zero. Get that tight then check your cam sprocket notch and groove.

You should describe this in more detail. Surging?

Actually that's the mechanical advance. When you twist it the advance weights move out against the springs.

The hose only gets vacuum when the throttle blade is NOT at idle. When the throttle blade is closed the vacuum is shut off. That's why you don't feel any suction at idle, but get more advance when the hose is connected and you give it gas.

Young people and COVID. Thankfully, I'm not at risk. My young days are past. https://www.yahoo.com/news/son-of-top-biden-science-adviser-suffers-from-long-covid-164911350.html Some people appear to experience long COVID even after only a mild bout with the disease. The phenomenon seems to have lingering effects on cardiovascular health and cognitive function. Patients also say they experience fatigue.

Bad news for Brits. Thankfully, the US is safe. https://www.theguardian.com/society/2021/may/18/any-amount-of-alcohol-consumption-harmful-to-the-brain-finds-study

England is open again! COVID is gone! https://www.gov.uk/guidance/covid-19-coronavirus-restrictions-what-you-can-and-cannot-do Gathering limits have been eased. Outdoor gatherings are limited to 30 people and indoor gatherings are limited to 6 people or 2 households (each household can include a support bubble, if eligible). People can attend indoor and outdoor events, including live performances, sporting events and business events. Attendance at these events is capped according to venue type, and attendees should follow the COVID-secure measures set out by those venues. I'm sure the NFL and MLS will be the same. They obviously don't know about the Skagit Valley choir. Most aren't even trying to fake it with a chin diaper. Plus the India variant. Karma?

You can do a lot with a timing light. Connect the light, start the engine, watch the light move as you turn the distributor. Disconnect the vacuum advance hose and rev the engine. Timing should advance (more degrees on the damper pulley as you watch the light) as RPM increase. Let the engine run at a speed slightly above idle (so that the ported vacuum will be applied) and reconnect the vacuum advance hose. Timing should advance considerably once vacuum is applied and drop when the hose is disconnected. Basically, you'll be leaning over a hot noisy engine watching the timing light flashes on the damper pulley while you work the throttle and disconnect/reconnect hoses. It's fun.

https://www.mcmaster.com/battery-chargers/

You had so much new stuff from the beginning and odd problems that it might be worthwhile to just go back and fill in some details. Who rebuilt the head? What did they do to it? Is the engine 1977 stock with dished pistons? Etc. Pinging is usually caused by advanced timing and/or high compression ratio. Seems like you set your timing on how it runs with no load. You didn't give a number though, for timing at idle. A number from your timing light would be good to have, plus verification that the advance mechanisms work as designed. Seems like you're close. If it's drivable that's a pretty good sign. Might be worthwhile to get back under the valve cover and recheck valve lash since it's a "new" head". Things wear in. It might be just me, but I tend to create a big circle of things I check when I have engine problems. Lots of verification of things I've already looked at before.

Have you taken it out for a drive? Given it a good thrashing? These engines like that. Engine performance with no load only tells you so much.

I have two of these. Bought the second after I thought I had lost the first one. They have a wide range of options, besides the typical charger. https://www.batterytender.com/Battery-TenderR-Plus https://www.batterytender.com/battery-chargers

This is correct. The injectors all squirt at the same time in the 280Z's. Swapping injector plugs is actually an easy way to test for spark or injector problems on a dead cylinder.

Any chance you disturbed the EFI power connection? The fusible link at the battery positive terminal.

Not stealth. https://bringatrailer.com/listing/1990-bmw-325is-47/

http://www.carpartsmanual.com/datsun/Z-1969-1978/body-260z-280z/2-seater/safety-belt

Which car are you working on? Funny, but I think that you need an R200 mustache bar so you might as well have dropped it with the diff anyway, if you're replacing an R180 with an R200. Shouldn't need to mess with the input/pinion shaft flange. If it's one of the early 240Z's with the diff set forward you might need a new propeller shaft. Or maybe it's a Subaru 3.9? Anyway...there's a solution out there somewhere. Good luck.

I went through that thought process myself and even managed to pry the mustache bar around and loosen a bolt here and there to get it out. But the procedure shown in the FSM is best. You can go one step easier and just remove the mustache bar also. I don't know why they don't recommend that way, since then everything is straight up and down. Load comes straight down, goes straight back up. The front cross member and mustache bar are good handles for stabilizing the load too. It's in the RA chapter.

Don't forget...

Actually, not trying to one-up anyone, but the vacuum advance on the Z's is ported vacuum. So it's closed at idle, no vacuum. But, if you have the vacuum advance hose on the wrong port you might get full vacuum advance at idle. Which would screw up your timing light reading and your idle timing. I'd hook up the light, then remove the vacuum hose. If timing changes the hose is on the wrong port. If you're still not sure of firing order and timing, then set your damper pulley mark at zero to ten and remove the distributor cap. The rotor should be pointing at whatever terminal is "number 1". Move your number one wire to that terminal and check your timing again. If things are screwed up then you might have a problem with your damper. Make sure you know where you started so you can at least get back there if things don't work.

Could be a restriction on the inlet. Easy to test with a piece of hose and a gas can.

Those are used on the 81-83 280ZX F54 block and 5 speed transmission. Earlier doesn't have the holes. Apparently it's an NVH reducing device. Somebody must have identified some flex between the transmission and engine block. They do look cool.

I don't want to be a buzz-kill but the CDC is making a "greater good" choice with their new mask guidance. Be careful. Know your local area. The CDC is thinking in terms of the whole of the United States and they and the federal government want to "reward" people for being good and getting vaccinated. Still a lot of unknowns out there, as far as variants, plus vaccinated people can still get COVID. Sorry. Buzzz....killed. Here's my region. Alabama looks pretty good now but you guys had some high numbers for a while.

It has been proposed that either today's fuel is not the same as in the 70's, or that the electronic components in the ECU's have aged. Either way, without a time machine your quest might be impossible. The AFM's from MSA seem to run rich. So one of those might get you closer. But might cause problems if you need to pass emissions. Good luck. I think that I already commented on the 180 versus 150 measurement. I don't think it matters. "Approximately 150 ohms" just means there should be "some" resistance.

This modification really is worth trying. It has worked for many many 280Z owners. The hissing might be the FPR. They hiss as fuel squeezes through.