Zed Head

You might check other things before you take it apart. If you didn't hear detonation or rev to 8 grand there's no reason for something to break. Could be something simple like valves getting loose. Rings on one side, valves opening and closing correctly on the other. That's all there is to creating pressure. I'd give it a good inspection and "re-tune" before taking it out.

"Toast" doesn't sound right. If it's freshly built it seems like the rings just didn't get seated correctly or are wrong for the cylinders. Might just need new rings. Just being positive.

The parking brake adjustment mechanism is designed such that it will not tighten the drums so far that the shoes rub. Pulling the handle moves the shoes, but the adjustment wheel only moves when the shoes get out far enough to get the arm over the next tooth on the wheel. After it goes over the tooth the arm drops back enough, in to the valley between the teeth, to let the shoe fall back slightly. The adjustment arm moves up and down in the valley between the teeth every time you pull the handle until the shoes wear enough to get over the top of the next one. If you have the mechanism working just crank way on the parking brake handle until the handle ends up in the same spot with each pull. Over time you'll notice that the handle pull gets longer then suddenly it will get shorter as you pass over a tooth. I rewrote this a few times, but that's the basics, I think. It's a pretty cool mechanism.

I'm not on the notify list, but feel compelled to say that there will be little to no benefit from swapping blocks. Besides that, you'd need new pistons, rings, etc. to fit the "3" overbore (is that mm"). It could get expensive and if the turbo engine is in good shape you're probably best off to leave it alone.

Never mind.

Could be I missed it. I sold the car so can't check. How does it seal without the rubber piece? Did you try it?

I've only read about them breaking for the guys that have V8's and abuse them.

Nope. I looked closely because I thought that there should be one. Then I thought "what a fine piece of engineering and manufacturing". The reality is that they didn't need one there, as shown by my leak-free cap.

2nd edit, actually a post...just curious. I wonder if people could pop their caps and see if they have rubber on there. To CO's last post's point. Just one of those curiosities.

Good catch. My Z didn't have one and never had a problem. The surfaces were both flat and sealed perfectly. It was actually a satisfying piece of plastics production. http://www.carpartsmanual.com/datsun/Z-1969-1978/engine-280z/cylinder-head

No gasket, just plastic. It seals very well.

Vertical would be the up and down part of the "T", the bottom. Horizontal would be the bar across the top. Follow the diagram, jump across the connection to the oil pressure portion.

Poke it, inside, with a screwdriver. If you feel metal it fell out. If it's rubbery it's still there. As long it's between the rod and the diaphragm seat when assembled it doesn't matter where it started. I don't know why they cal it a "reaction" disc. It should be called a damper or something similar.

Hello @EuroDat I am pretty sure the switch opens when pressure is reached. A person could study the relay system diagram, and get a headache, or just work from the knowledge that if you remove the sender/switch plug (creating an open switch circuit) and turn the key on the pump will run. So you would want to wire up your 2nd relay to be open when power is applied through the key, then close when power is removed as the pressure switch opens. I think that leads to using 87a, normally closed when their is no power through the solenoid. It's a rare case of using the 87a circuit. Key on, the solenoid energizes, the 30 circuit is open, no power to the pump. Engine starts, oil pressure builds, the switch opens, the solenoid deenergizes, 87a is actuated, 30 gets power. I think this is right. The fact that you can pull the oil sender/switch plug and make the pump run is a well-known flaw in the design.

Probably doesn't matter much. You have an L28 in your car because that's the easy way to get more power. The L24 will probably be worth something to somebody some day. The question is whether or not you want to be the keeper of the block. I'd give it away on Craigslist. Some Z head out there will probably take it and make something good from it. I sold my L28 engine for cheap after I replaced it with a better one. I knew I'd never do anything with it. Take the front cover and thermostat housing and other odds and ends that you can use on your L28 and give the rest away.

Are you sure it's an L24? How does the crankshaft look?

Weird. I did a little Googling and found what looked like an interesting "official" Nissan web site. But it has really bad information on it. Just flat wrong. https://www.nissanusa.com/experience-nissan/news-and-events/nissan-z-car.html THE NISSAN 280Z The next of the Datsun Z-Cars to launch was the 280Z in August 1978.

My learning was that 77 was the 4 speed with a 5 speed option, and 78 was the opposite. There's probably sales literature out there somewhere. Release the Google...

You might swap your rear wheels for the fronts while you have things apart. See if the wobble follows the wheels. Of course, then you won't know if it's the TC rod upgrade or the wheels. Maybe take a for a test then swap if it's still there.

Should have a thermotime switch, with an injector-type plug, and a coolant temperature sensor, also with an injector-type plug, and a temperature sender, with a single wire attachment. Later cars have a fourth switch, for the vacuum advance solenoid.

Actually, heat soak has been a big problem with the 280Z's. We've had some good discussions about it in the past. Although, it's possible that the fuel blends have changed over the last few years and it's not as bad now.

The COVID is giving people lots of free time to spend their money on the internet. That is a nice looking example of the $199 package. Odd that it came with a 4 speed though, I thought that the 5 speed was standard and the 4 speed was a requested change.

Have you checked the resistance at the ECU plug, on Pin 13? There are many possibilities, including a PO "tuning" around a problem instead of fixing it. Could be vacuum leaks. Could be something else. Another cause for popping back through the intake is a flat cam lobe. Hope that's not it. You really need to spend a little time at the ECU connector with the 1980 Guidebook and a meter. It has all years through 1980. Make sure everything is right before trying to fix things. Odds are though that the fuel tweak will still help after you get everything right. So that's not wasted time/money. You should check your fuel pressure with the engine not running also. If it can't get higher than 30 that's a problem. EFI work is just a long list of small things.

The fuel tweak was for the popping and stuttering, not the idling. Are you sure that you're disconnecting the sensor? There is also the cold start (thermotime) switch and the temperature sender in the same vicinity.

Here's 82. The easy way to check is with a meter or continuity tester. The switches close when the condition is met. Top gear, reverse, etc.