Zed Head

Check the seat in the switch itself. A bright light and a good look will usually show you the seating/sealing surfaces and if you're getting full contact around the circumference. Looks like you found your air leak though. Air has much lower viscosity than fluid (of course), you can suck a lot of air in where just a few drops of fluid come out.

Your problem sounds a lot like mine when I had the bleed screws on the bottom. But yours are on top. What method are you using for bleeding? The MC's can leak internally, the seal for the fronts can blow and the fluid just washes back and forth over the seal as the piston moves. And quality of aftermarket parts is poor, in general. Parts from the same manufacturer might have had the same unskilled person building many MCs in a row, repeating the same error. If you decide to try another MC try a different brand. I'm going to bet on bleed technique though.

Does the pedal go to the floor or does it stay high and firm? If it goes to the floor can it be pumped up? The pistons don't move far at all under normal operation Are you saying the the wheels still turn with the pedal down? Not really clear...

Red on(in?) white 72. A "survivor" by my standards. Looks pretty good. Very little salt used over here and when it is it gets washed away by gallons of roadspray pretty quickly. https://bringatrailer.com/listing/1972-datsun-240z-205/

You might squirt some oil in the cylinders too. Your low pressure numbers might be because the pistons aren't drawing in the air. Could also be that your carbs aren't working right. You don't know that the float bowls are full. Starting fluid answers a lot of questions. Big time saver.

Use something more flammable. Starting fluid, carb cleaner, hydrocarbon brake cleaner. Or gasoline. And make sure it gets past the pistons in the carbs in to the runners.

What fluid did you use?

The compression number range is not terrible. 12.5% on #4, the worst one (actually 15% - 25/165). The equipment used will affect the readings. And the lash readings do show lash so the valves should be closing. Maybe the engine spins fast because you have a powerful battery. You have reasonable cylinder pressures and the engine is spinning. The engine should start. So, spark is left as the unknown. With the engine spinning that fast you should be able to get a nice stable ignition timing reading with a timing light. If you can do that, it will tell a lot. And, there are no pictures of your spark plug wiring. Might be that they are incorrect. 1 5 3 6 2 4 counterclockwise. Spark and ignition timing seem like the main unknowns at this point. They have not been confirmed.

That is the opposite of how it's done. First or second thing I would do is remove the valve cover, take a.006" or thinner feeler, find a lobe that has the point pointing up, and see if you can slip the gauge between the round part of the cam shaft (no lobe or ramp) and the rocker arm. Do that on all of the lobes that are one the base circle. Won't be a surprise if you can't get the gauge in. Or, get a cylinder pressure gauge ( I think that you can borrow them from a local auto store) and measure cylinder pressure. It's easy to do. If you get low numbers, then you can get under the valve cover. If lash is correct it might be that you have bent valves. There is an odd noise about every rotation in your video. Doesn't sound good.

Sakura Garage is @cgsheen1 and his son, I believe. No surprise that they figured things out. Might be that the problem was an opening and closing issue. The flow test was probably just wide open. The rig for pulsed testing is kind of spendy and more complex. I wonder if the "bad" injectors were original or aftermarket.

That's a good summary. The aftermarket guys probably went cheap on their design and just grind the tip in to the bottom of the hole or let it sit above the bottom, not contacting. I was wondering about the washer also. No point to it if the sensor tip is supposed to make contact.

Engine spins way faster than it should. Like there's no compression. Have you ever measured cylinder pressure? I posted this picture of your cam lobe earlier. It looks like wear on the base circle which should not happen. Like there's no valve lash. Who last adjusted valve lash on the engine? Looks and sounds like the valves are all hanging open.

I agree. But thanks for clarifying, I think that you are right, Obviously. Now that you bring it up, I do remember the bottom "spinny" portion on the ZX parts. So, maybe, probably, it's just a one-way possibility. You can put a Z sensor in a ZX hole but you can't put a ZX sensor in a Z hole. Or maybe you can't do either, although I think that Av8ferg did, if I read his words correctly. He should be just fine, right? I was surprised at the prices. Things are getting expensive in Z world. So, a one-way swap, Z part in ZX hole, looks reasonable. Might help the wrecking yard and CL searches also.

If you read Diseazd's thread you'll see that he was too. That was the point - the MSA recommendation did not work correctly.

The main reason I let them know is so that they don't have a problem that goes on for months or years, damaging their business, because they did not know about it. They've been around since land lines but things are changing. Trying to help them keep up.

These two were at the very end of the search I posted. Searching is definitely more difficult than it used to be. Hard to find the right place then get it to do what you want it to do. I used the CZCC function this time but usually I just use Google and "site:classiczcars.com"

That box is the junction point for the wires from the distributor to the wires from the ignition module. With the factory setup there would have been a green and red wire from the distributor connected there too. On a reman distributor the wires are blue. Since your ignition module is connected to your distributor in the engine bay, and the ignition module inthe cabin is disconnected, the wires at the 6 sided box aren't connected to anything. They can just sit there. Here's the 78 wiring diagram that somebody colorized. They don't show the full shape of the terminal block.

The resistance versus T is the same. Fitment would be the issue, I'd guess. Might be that Nissan just modified the connection part because it had a tendency to fall apart like mine did. From the 1980 EFI book.

Other manufacturers have moved to dry cylinder head temperature sensors. I have a Ford that has one and they actually use the reading for the "coolant temperature" gauge in the dash. And, it turns out, they just set the needle in the middle if the temperature fits within a wide range. Anyway, on the Z's Nissan went to the head sensor with the P79 and P90 heads in the ZX's. They look almost identical. The part numbers differ by one digit. Actually, now I see the difference. But I think that they have the same thread and can be interchanged. I accidentally pulled the guts out of one of mine trying to remove the connector. It's just a dry hole with a thermistor and silicone gel inside.

@Joseph@TheZStore @Greg@TheZStore @James@TheZStore @zcardepot.com

Hope you guys don't mind, I'm going to "at" the MSA guys and ZCD. ZCD never responds but I think that he does read the posts. The guys at MSA usually respond, and seem to address issues. The penny-saving on shipping seems like a new one though. @Joseph@TheZStore @Greg@TheZStore @James@TheZStore

Nissan used BSPT on their tapered plumbing fittings. You could probably take the old piece that fits in the hole and "machine" it to look better. Chop the connector off. I think that they all have a sealed well inside for the actual sensing element. Or maybe find a plug on McMaster Carr. Check/uncheck the boxes on the side to change the display. https://www.mcmaster.com/standard-pipe-fittings/thread-type~bspt/brass-and-bronze-pipe-and-pipe-fittings/type~plug/ The straight thread is probably BSPP. https://www.ralstoninst.com/news/story/the-difference-between-npt-bspp-and-bspt-seals

It says "lock preventing". I know it's just a translation error. Interesting though. There are better terms - current lockout? Current cut?

If you have the factory ignition module you should see battery voltage minus resistance drop, then it should go to battery voltage after 10 seconds (no current). For what it's worth. Not really sure why they call it "locking".

https://www.classiczcars.com/search/?&q=damper&author=Diseazd&search_and_or=and&sortby=relevancy