Zed Head

Could you set up a test bench to measure module performance against RPM? Look for timing changes and/or reduced charging time. I think that that is the issue that Vizard had with the GM HEI module. As I recall he proposed it but never actually showed that it happened. I think I've written about it in the past. You could even blow up some modules by leaving them ungrounded or with poor cooling. Only $25 / experiment!

Are you taking questions or will you just be adding things as you explore? You had more in Av8's thread, with the Z wave form, compared to the ZX. Still wondering why this forum doesn't have Stickies. So many good discussions are buried back in the past.

Official Nissan material or something else? Do you have a reference? I'm pretty sure that the injectors do boil dry at times, it fits with the heat soak/hot start problem.

There are 38 posts in this thread so I might have mentioned it already. But I modified my 76 filler neck to take an unleaded nozzle without falling out. Not clear what you did but that would be an improvement (I think). You cannot hang a nozzle from the huge 76 opening. You have to stand there and hold it.

I have many questions. Can't wait. Maybe some Pertronix or 123 modules can be looked at, to compare. Or David Vizard's 4500 RPM limit (V8) for the HEI module. Many unanswered questions floating around out there.

The fact that the engineers must have designed algorithms that converted degrees to time (very small intervals of time) in to the ignition system has been in the back of my brain since I started learning about them. I wonder how accurate it could actually be. And it must be more accurate at low RPM. I wonder if weird stuff happens if you use the retard setting at high RPM. It would be interesting to compare high PRM timing between the two modules. I've always read that the GM HEI module used a positive crossing trigger. The rising edge. But, another thing that's been in the back of my mind is that silicon transistors switch at 0.7 volts, apparently (not a semiconductor expert). People use the GM HEI module in place if the "ignitor" on the 280ZX Turbo ECCS ignition systems. Which should never go negative, it should just have a zero to 5 volt square wave. Maybe the HEI module has circuitry that works on a zero transition though. Not my field. If it has to cross zero it should not work in the ZX ECCS system. Anyway, it was fun to learn something new about these two modules. Lots of interesting stuff about the GM HEI modules in the Megasquirt world. http://www.megamanual.com/ms2/GM_7pinHEI.htm

That is a weird one. It's not really what was suggested, which was old parts being used up during the transition. That one has parts that are not supposed to be in use yet. Any chance somebody just wanted the "improved" parts and had them switched later?

Earlier it was supposed that Nissan used "old parts" during the transition to the "late 1971" 240Z. If I had one I'd just use Nissan's bulletin as a check list. Actually, if I was selling one I'd do the same. It covers the issue of features, and the time and VIN just fall out of the documentation and ID tags. Just put the numbers and the features out there and let the buyers decide what they value. It would be interesting to see if there are any hybrid early/late 1971's out there. Late parts used earlier than shown (like the reversible key) or early parts used later. http://zhome.com/History/New71LateP2.htm

The question I raised is whether the timing is retarded or not, meaning that the timing would change when you switched modules. Since you would normally set the timing for just one module after installing it you wouldn't know if the retarding mechanism was in play or not. It's not about how it works but how the two different modules compare. Even the base setting, of either, might have a delay based on the internal circuitry. A timing measurement will tell.

It would be useful to know if the initial timing changes. Apparently the E12-92 retards timing by 8 degrees, but it's not clear exactly when. Probably when the engine is hot and the throttle at idle. For emissions. Retarded is cleaner. That's how the 280Z systems work, but with two pickups in the distributor. When the engine is cold the timing is kept advanced at idle to help with idle RPM. Not super clear how the ECU is involved unless it completes the ground based on engine RPM or some other condition. Anyway, in your video you can see that idle PRM are lower for the E12 module. That is what retarded timing will do, cause idle PRM to drop. So, it might be that for your tests timing is retarded by 8 degrees for the E12-92. A quick check with a timing light would answer that question. Then you'd have to decide if you want to figure out how to make the two modules match. But, the fact that it runs means that it is serving the fail-safe function, to get home if the HEI fails. p.s. here is the 280Z description for the two pickup distributors. When the circuit is open timing is retarded. Which would fit with having the E12-92 pins disconnected. I think that you'd have to run 12 volts through those extra pins to get the timing advanced to match the HEI module. Thanks for letting me fill your thread with extra stuff. An interesting puzzle.

$21,750 for a sketchy 71 240Z, modified, no ID plates visible. There is no predicting the market value of a 240Z.

The E12-92 has an extra pin that adjusts timing through a temperature switch. Might be that when you switched to it you inadvertently changed your timing. I thought that you had an E12-80. There's not really a good reason for a performance change unless the E12-92 is failing, or something else changed. p.s. some people say that you have to short the extra pin to ground or run power through to stabilize the timing. The 280ZX FSM probably shows how it works so it could be figured out. Really though, you're about ready to just move on from the old Nissan parts. I'll just pile a couple more things in here for anyone with an E12-92 in the future. Notice the idle switch and the thermo switch connected at the "IC". Somebody with electronical experience might have fun figuring out what Nissan was doing here. Last, maybe, edit - here's a zcar.com post from way back, with a reference to 240260280's friend Wayne Monteath. Apparently, it doesn't matter if the extra pins are connected or not but the question would be where your initial timing is when you switched. https://www.zcar.com/threads/e12-92-or-e12-80.116513/

This one is already up to $15,000. Funny though, the guy has been driving it with no air filters. Had the carbs rebuilt, just never put the filters back on.

This modified 71 is probably going to outdo the "early 71 Series I" 240Z. It has fender flares! Eeeewww.... https://bringatrailer.com/listing/1971-datsun-240z-231/

$12,300, RNM. Presentation is key on BAT. The seller did a not-so-good job.

I think it has something to do with the way the fuel is metered from the carburetors. With EFI the air flow is fairly precisely measured and the appropriate amount of fuel is added to balance the air. With carbs the fuel is pulled up from the float bowls and basically spilled in to the air stream. There are emulsion tubes and other things but still the fuel gets pulled up in to the air stream, more air = more fuel. If you have pulses of air from a lumpy cam (inconsistent air flow/vacuum) the fuel gets bounced up and down and accuracy/consistency is lost, plus the fuel does not stay well-atomized. Carbs work best with smooth air flow through them. EFI averages out the pulses back at the AFM or MAFS so is not as affected by a lumpy cam. That's my basic understanding.

The 70/71 is up today. Let's see what the collectors think, if any are interested. https://bringatrailer.com/listing/1970-datsun-240z-82/

You're saying that a 1973 240Z has the same value as 1970 240Z? That if you had a 73 you'd trade it straight across for a 70? Because they both say 240Z on the outside. Trying to use those played out memes will drag you in to absurdity. Be careful.

Actually, my post wasn't about the easiest way. It was about the best way to be sure both ends were correctly seated. Your bobbly speedo sounds like the cable is not fully seated and it's rubbing on the inside of the sheath. It's bound up. Or it might be that you have a bad spot on the gears. At least you know that the parts all work.

Yes and yes. There are two possible reasons that the cable is not spinning the speedo/odo parts. 1. There's enough slack in the sheath that the drive cable can get jammed up and not engage correctly. It helps to pull the inner cable out at the transmission and stick it in to its slot on the transmission end then push it back up toward the speedometer as you screw on the sheath end. At least that helped me. Apparently the speedo end seats more easily than the transmission end. I think that I had also spun the propeller shaft while I did that. I had the back wheels up. 2. The housings are different. The locking slots are oriented 180 degrees apart. The gears are offset so if you use a ZX in a Z the gears won't mesh. Look in the hole and you should be able to figure out which one you need. You can also reorient it without locking it down and see if it engages. Some people just grind a new slot in the housing when they do a transmission swap. But it's pretty easy to swap the gears too.

That's the original round style that they used on the 260Z's. The 280Z's used the rectangular one like in the drawing you posted. It looks just like the drawing. It's folded over then taped up, so it's a different shape of lump.

I had a similar thought. Or put some colors/label on the wires and the module pins. I had a module crap out on me in my garage after some engine work. Forgot to put two plug wires back on. So they do fail for various reasons, but so do the originals. I carried a spare module and the tools need to change it in the car. I also had a spare ECU behind the seat.

There's no need to get it out. Just verify that the lump is there. If the tape is unmolested you migth as well leave it. Remove all of the existing wrongness and see where you're at.

It's a lump in the taped up harness. Like a frog in a garter snake.