Zed Head

Keep turning the knob until it takes off like it should. You should be able to make things so rich that the engine won't run, you can flood it. Then go back and do something else to try to get the idle leaned out. That's the game, tuning the untuneable EFI system. With the aftermarket systems you change things by computer. You'll need to do mechanical and electrical things directly.

The 280Z's have another knob right next to it for the trip-meter. Turning it won't dim the lights.

George's dad died...

Take a picture. Did you turn the knob?

If you didn't bend anything you could always go back to stock bushings. They seem to be available. If you mean the casting when you say "assembly". You''ll be back to where you started but with new rubber. http://www.carpartsmanual.com/datsun/Z-1969-1978/axle/rear-suspension/57 https://www.nissanpartsdeal.com/parts/nissan-bushing-link~55541-e4100.html

If you have a spare distributor and an ignition module (unless it's a points distributor), and a coil and a terminal wire and a battery, you could make your own tester. Spin the distributor, make sparks, watch the tach. Wish I had parts, it would be fun.

What do you mean by "redo"? I like to use carpartsmanual to see if part numbers changed. Looks like the control arms, AKA transverse links, changed in august 1973. Not clear what the change was though. The axles changed in the cast hubs, somewhere in 73 for the 74 model year, but it looks there were a bunch more changes along the way. Part #1 and 2. http://www.carpartsmanual.com/datsun/Z-1969-1978/axle/rear-suspension

I wasn't joking here. 2200 ohms is a lot of resistance. If the tachometer circuit already has resistance there's no reason to add it in-line. Unless it's for flyback(?) blocking, from the coil discharge. I'm going to guess that without the resistance in the circuit either the tach won't work or the ignition system. Could you measure the resistance through the connection at the tach to ground? That might offer a clue. It's probably in the schematic but in the meantime. I'm not an electrical engineer, I'm just trying to figure things out.

My comment was just from the basics of Venturi and Bernoulli. Where did your pasted picture come from? Actually, there's a balance between air velocity and pressure and needle position (effective orifice size). That's where things get messy. As I understand things the oil controls the rate of piston movement, the speed, but not the steady state. In other words a thick oil and a thin oil should put the piston in the same place at steady RPM. I'm no carb expert but a set of stock carbs might be a good starting point just to see how the combination of engine parts work. Then go to the "upgraded" carbs. You don't really know what has been done to the ones you have.

Round port should work fine on a P79 head. The P79 and the N47 both have exhaust liners that are smaller than the hole in the head casting. It's the liner opening that needs to match and it's round. The liners are designed to get really hot and burn off carbon and, maybe, excess fuel and oil. Keeps the exhaust system, and the exhaust cleaner. The first picture in this link shows the port. You can see the liner in it. http://xenonzcar.com/s130/Heads.html

One possibility is that the pistons aren't rising when the throttle is opened. This keeps the needles low, reduces fuel input to the air passing by, and makes things lean. The pistons' rate of rise is controlled by the damper oil. So, it seems like you have sticky pistons. What kind of oil are you using?

I would start from scratch with this. What are any and all possible causes for an engine to lose power when the throttle is opened?

You're right, I grabbed the wrong drawing. Screwed that one completely. Redo...

Found some good reading. Sure to help a person move up in their career, after things get back to "normal". https://thecooperreview.com/10-tricks-appear-smart-meetings/

Break out that meter and rerun some tests. Sounds like you lost power somewhere, or ground, or the Pin 1 signal. Can't swap until you know what to swap.

Ooops.

It's a lump in the tape of the harness. It's shaped just like the picture. It's in the vicinity of the ignition module. If too much current flows through the tachometer the coil might not discharge. Make then break. No break, no spark. Maybe why it's 2200 ohms.

I'm not sure how idle mixture is set. Usually there's a separate circuit for that. That's the carb tuning game, balancing the various fuel circuits. But at 1/4 throttle you're probably "on the needle", so raising the needle will let more fuel get pulled though the main jet. I'm just winging it from past carb memory. But I know that there's a lot of back and forth and trial and error involved. Good luck.

I think that people call that the "pedal box". Make sure that you get all of the parts that come with it. $350 still seems steep and I don't know if "Series I" matters. The 240Z guys know, I've done my communications monitoring... http://www.carpartsmanual.com/datsun/Z-1969-1978/brake/brake-clutch-pedal I have a memory of @cgsheen1 knowing a lot about this.

Makes more sense. The odds of it being original are slim, and if it is it's probably worn out. It looks like you're doing a restoration so maybe even original mechanical parts are important. But $350 for a worn out clutch disc and pressure plate seems a bit much. If that's what you're looking for, original parts, make sure you check the markings and labels. I can't believe that somebody would even ask that amount for those parts. Get pictures, post them, and we'll tear them apart.

I don't think that there is such a thing. If the parts are Nissan new old stock, they might have added value. But "series 1 clutch assembly" doesn't really mean anything and doesn't say anything about the brand or what the parts are. How about more details?

A few good deals. 76 had an ignition module also. https://www.rockauto.com/RSS/vehiclefeeds.php?carcode=1209260&m=wc&l=en&html=true https://www.rockauto.com/RSS/vehiclefeeds.php?carcode=1209226&m=wc&l=en&html=true

I would let go of the assumption about the needles. Can you raise the needle to richen the mixture? It's obviously lean. There's a lot in the news these days about trusting the facts. Your facts say that you need to make things richer. No matter what you thought was supposed to happen.

No, I just meant the numbers. 80,000 people dead. More than WWI combat deaths. I've given up on the mask worries, people do what they do. Just like drinking and driving. And now kids are are dying from it also, through a different route. That might actually be what changes things. Parents. Not "old people" dying. Even if you assume a low percentage of the 80,000 old people, it's a lot of kids. And a lot of worry. 1% x 80,000 = 800 kids dead. https://discoveries.childrenshospital.org/covid-19-inflammatory-syndrome-children/