Captain Obvious

Welcome to the club! You are reading the manual correctly. There should be nothing connected to the anti-stall dashpot. Even though it looks like a vacuum nipple, there shouldn't be any hoes on it. The dashpot should just be left open. And a couple of the other vacuum lines are mixed up accordingly. The non-California 76 cars (which it appears yours is) used a system to disable the distributor vacuum advance until the car is in top gear. Not sure why they thought this was necessary, but in 77, they decided this was not necessary and eliminated that feature. So if I'm reading the manual correctly (pages EC-9 and ET-1), it appears the three-way line from the throttle chamber should go to: Throttle chamber connection Carbon canister control Timing control solenoid valve And then the other side of the timing control solenoid valve should go to the distributor advance connection. So where in PA are you?

I'm glad the story was that boring! Although a harrowing hair raising saga would have been much more entertaining! And I'm also glad that you've got a set of hubs put together now that are issue-free. And if you've got a gap between the flange and the outboard bearing, that's definitely a raging clue as to the previous issue. 1.6 thousandths can be a LOT when talking about bearings. Just for forensic analysis... See if you can determine if that gap is the same all the way around the bearing. If it's the same all the way around, in theory it shouldn't cause what you saw. But if it's .0016 on one side and zero on the other (which is what I suspect), then it's indicative that something is bent or you got some piece of grit or metal shaving trapped under the bearing race. In any event, it's almost definitely related to the problem.

I don't think the contact cleaner drying out is what is causing the change. I think there's something else going on. Are you sure something is really changing, or is possibly a placebo effect?

Clearly (and not surprisingly), there are people viewing both this ClassicZ thread and that BAT sale. Right after I brought it up here, they started talking about the dash cap on BAT and they're all over it now. It's an easy issue to fix. Expensive, but simple. "there has been some discussion of this car on a prominent Z car website, Classiczcars.com" Woot. We're prominent!! So just to be clear... I don't see anywhere where the seller ever portrayed this car to be a "completely correct" example. So all the chatter from people (like me) about the things that are "wrong" is info for the next owner who wants to make it better. That car isn't done, but it's a beautiful starting point!

Beautiful car. I took a quick look through the comments and I think there is more of an issue with the tone of voice being used to point out some of the incorrectness, rather than the incorrectness itself. The insinuation of questionable intent: "i just find it to be very strange how you own over 15 Z cars and you dont know ...... Just like you didnt know .... lol. or maybe for some reason you are pretended not to know but indeed you do.. what ever it may be." Uhhh.... OK. Something I see that I'm surprised that hasn't been mentioned... That's a dash cap screwed into place, right? That bugs me. Also, the shift knob... It's the "right" Nissan knob, but it's still wrong. And there was some discussion about the carb correctness... The car is said to currently sport three screw SU's and the seller says they are the correct carbs for the year. I though three screws were used in 72 only? I'm no expert, but I thought a 70 car should carry four screw SU's.

Oh wow! That's cool. And brave!! Those sort of journeys are often good stories. Was it an entertaining eventful journey, or was it a smooth sailing boring story?

I like the shot next to the original wood knob. That's a great contrast between old and new!

Haha!! Good luck! So out of curiosity, what year are you working on anyway?

I was taught that if one foot on the floor didn't stop it, you should put two feet on the floor and get up. You aren't going to fall asleep anyway.

Great news on the polarity confirmation. And also great news that the engine is running well! Don't forget to put a timing light on it though. You do still have to set the base timing.

My son who recently graduated from VT went through that exact same thing. There was one class that was questionable up to the end and nobody could be 100% sure until the diploma arrived in the mail. Hope it all works out!!

Haha!! My engineering sense tells me that the boundary condition would be when/if the pendulum ever reaches forty-five degrees to horizontal. Beyond that, it would be unrecoverable because the force pulling down would be greater than the force you could ever create even if you moved it laterally at infinite speed. At least that's what the vectors in my head tell me. And you're right! It's beer time!! Right now! Good night folks!!

Can't wait. Hopefully we have a smoking gun. It's always a great feeling when that happens!

I also believe that the original ignition modules are looking for the negative to positive going transition. And as Zed Head mentioned, if you get them hooked up backwards, you end up with a lot of spark scatter and unpredictability. It's because you are spending a whole lot of time in the transition zone with a slow changing signal. Kinda like a very slow ramp on a CMOS input. They don't like it and can go indeterminate. You want the slope as vertical as possible and if you get it hooked up backwards, it can go metastable. The only predictable area is physical transition when the reluctor stops approaching and starts retreating. At that point, the magnetic field change reverses, and the induced current will reverse as well. And... If that's not all... (we talked about the amplitude before being proportional to the speed of rotation) When designed correctly, the signal slope at the transition point is relatively unaffected by the rotational speed unlike the slope elsewhere which is very dependent on rotational speed. If I haven't beaten this to death yet, here's a pic showing the waveform with the polarity switched. Note that the important positive going transitions are that flat indeterminate area with almost zero slope. Bad. What you really want is infinite slope on the positive going transitions. Here's the wrong polarity: And here's what the waveform should look like. Note that the positive going transitions are the vertical slope areas. Correct polarity:

I disagree. I know it's all past news now and doesn't even matter, but I would have done it differently. I would have ignored the motor, the drive amp, and all the rotational stuff at the left end of the track. I would have also ignored the viscous damping. Focus on the forces required to keep the pendulum vertical. Write those equations first in a perfect simplified world and then once you have that part done add in the complexity of the damping and a rotational drive. But to start, assume linear motion, frictionless surfaces, and no damping. First task is to just keep the pendulum upright. Once you have that, add in the other factors one at a time.

That's one of my favorite Far Side cartoons ever. I've even heard that "My brain is full" phrase uttered in technical project meetings. Maybe even by me...

You do know that the signal coming from those VR pickups is polarity dependent, right? Even though it's an A/C signal, the phasing is important. So my guess, based on what I'm reading. is that you had it hooked up backwards earlier on, but with all the alligator clipping and such, you "accidently" swapped the polarity and got it connected properly. And FYI... That's the reason they used two different sized lugs. That forces you to get the polarity correct when you make the connections to the terminal block. The posts in the terminal block are sized such that you can't connect it wrong. Poka-Yoke.

Sorry to hear that. Since you came to us two days before it was due, you were clearly desperate. (As evidenced by the fact that you came to us! ) Well it at least sounds like the grades going into that project were good enough such that even a poor grade on that one, there was enough cushion to maintain a passing grade for the semester. Hopefully that's the case. The wording of the assignment made it sound like it was a group project... Was there input from other team members? Or despite the description, was it an independent effort?

So how did this turn out? Or don't you want to talk about it?

Remember that engines don't want to run slow and they hate running at idle. They also hate running cold. So it wouldn't be unusual for it to run poorly until it warms up. But once it warms up, it should be much more robust. And once the engine warms up the WTS should be about 250 Ohms. So if it runs better at 2.5K even after warm-up, then there's something going on. If it wants a higher resistance on the WTS, then it sounds like you're running lean. But for confirmation, you should be able to do some quick and dirty tests to see if it's rich or lean. I know you already know this stuff, but just in case: I assume you've got some of the vacuum connections on the intake manifold blocked off with rubber caps? Like the brake booster connection? You can pull the cap off a tiny bit to manually modulate some additional air into the intake manifold and see how the engine reacts. If the speed goes up and it steadies out, then you're probably running rich. If it get's worse and starts to misfire, you're already lean and making it worse by letting extra unmetered air in. Move slowly though... A little bit of air here can make a big difference. You can also adjust the mixture by moving the AFM position around, but same thing... A little motion there can make a big difference. It's squirrely. Have you ever taken a measurement on the ATS? It should be reading about 2K Ohms at your ambient this time of year.

@Av8ferg, Where did you get the O-ring and lock ring for the fuel sender? I'd like to pull mine out and figure out why it's not accurate, but I would like have an O-ring and lock ring on hand before I take it apart. I'm assuming if I have new ones here, I'll be able to re-use the old ones.

Haha!!! Thanks for the coverage!!

I'm not a timing expert, but I wonder if you would even see much of an impact at no load condition even if the advance mechanisms (centrifugal and vacuum) were working at all. I mean, on the road under load, you'd be losing lots of power and would certainly notice it. But under no load conditions, I'm not sure you'd see much impact. I can't easily disable my mechanical advance, but maybe I'll try disconnecting my vacuum advance and seeing what happens. As for the distributor signal to the ignition module... The VR is just a changing magnetic field cutting through a coil. The faster it changes, the higher the induced current and the higher the voltage that could be generated in an attempt to push it. So yes... The output voltage is proportional to the rotation speed. That said, however, it has to work well enough at starter cranking RPM or the engine would never even start. And I'm assuming your starter spins a lot slower than even a low idle speed.

IIRC, there are no ground connections to the EFI harness other than the large wire that leads directly over to the battery. All the other connections (other than the thermotime) are derived inside the harness from that one single ground. I don't think the distributor pickup is supposed to be grounded in any way. In fact, in an effort to prevent noise pickup from any other sources in the car, it's twisted pair to reduce antenna loop area. I haven't looked at in depth though. On my 77, that terminal block does not connect either side to ground. Don't know for sure about 75. I also believe the electronics portion of the AFM is floating and not grounded inside the case. So if they ground the AFM case, it's most likely another interference prevention technique. Faraday cage. Grounding the ECU case as well would do the same thing. All the electronics inside are floating with respect to the metal shell, but it can help to reduce outside interference from things like the ignition flyback. In the end though... I doubt any of that is the root cause of the problems you're having. Sounds like it's getting better though!!! Step by step!

Can't touch this.