Captain Obvious

Man, he's got Z-itis bad. Really bad. Multiple generations bad! Hope the two of you find good homes for the thinned herd. I would be skinned alive if I brought something else home, but... Have you got any pics of the GTO stuff? I just like looking at them.

I'm positive you wouldn't have sold more than a couple. I assume you never turned up a source for the internal rubber parts or the end seals? Speaking of such things... I'm positive the Z isn't the only car that used those internal parts. Anyone have any theories of other cars that may have used the same internal conponents? Something easy to find like an old Maxima or Sentra perhaps? Anyone know if Honda or Toyota used Hitachi brake components?

That's fantastic!! You must be so happy!!

Haha!! I'm not sure it's worth a rung of the cool ladder, but I've only ever bought two brand new vehicles in my life off the dealer lot, and this is one of them. She's an antique at this point! I'm not sure how much longer I'm going to retain ownership though. Riding around seeing everyone in their SUV's driving with one hand on the wheel and the other hand on the smartphone... It's out of control. I'm the one that's the most vulnerable. I used to ride more, but phones and inattentive drivers have taken most of the joy out of it.

Now there's some good documentation for ya!! Way better than what I could turn up! Kudos!! Phil, So the connector in your original pic goes to the speed control switch, right? Not the resistors on the blower housing. If that's the case, then I suspect that B/W is for the A/C system.

Glad to help. The documentation got way better as the years went on. Those first couple years were sketchy on some of the sub-systems. By the time they got to 77 (my year), things were pretty good. Interesting to note, however, that even in 77, they used a similar sub-cable for the HVAC system. The colors and positions of the wires are different, but the concept is the same. So if that cut-off blue wire is supposed to provide power to the blower fan, then the other end should plug into a bullet connector on the dash harness. Have you found the other end where it is supposed to connect? I believe it should be blue as well.

I haven't measured it, but I'm surprised at how low your AC readings are for the VR output. Kinda makes me wonder if maybe you're dragging the voltage level down by asking the coil to drive something of lower impedance than it was designed to interface to. In your drawing above, you mentioned "Hall pickup"... If the coil signal input of the system was designed to be driven by a Hall Effect sensor, then it's conceivable that it's expecting to be connected to an active driver instead of a passive pickup? Maybe they're driving a pulse transformer or the LED input of an optocoupler with the ignition input signal, and the VR pickup just doesn't have the ummph to provide the power at low RPMs? If I were designing the ignition input section of a system like that, I would want to provide galvanic isolation of the signal pickup, but I would buffer it on the non-isolated side first and then run it through an isolating device like an optocoupler or transformer... AFTER I had amplified and buffered it. Kinda hard to test (because the distributor has to be spinning), but I wonder what the pickup coil signal looks like when it's NOT connected to the Spitronic module. If it's a lot higher when running open circuit, then maybe the Spitronic input impedance is dragging it down.

And (just because it's Z related?) here's a neat shot of my home built level manometer being used to sync my cycle carbs. And you can see a corner of the Z in the shot as well!! Nurse!! IV STAT!!!

That bottle manometer style won't work for the Z application, at least not in stock form. In order for that device to work, you have to be able to isolate the engine side (high vacuum side) of the two carbs from eachother. Problem is that the Z carbs are tied together by the balance tube. In order for that manometer style to work, you would have to block off the balance tube passageway somehow. You would also need vacuum ports on the engine side for both carbs, and I don't believe those exist for the round tops. IIRC, the front carb has a vacuum nipple, but it's ported vacuum, not full vacuum. I don't believe the rear carb has any provision at all for a vacuum connection. So the bottom line is in order to use a manometer style device like that, you would have to disable the balance tube and you would also have to come up with a way to supply two vacuum nipples, one on each intake manifold. (The aspiring creative inventor could suggest that a pair of nippley devices could be bolted to the intake manifolds where the balance tube usually goes that would both segregate the intake vacuums AND provide vacuum measurement connections at the same time.)

Providing closure to this project. My power brakes work again, and the booster holds vacuum overnight, so I know it's leak-tight. I put my sticker on, and I'm calling the project officially "done". Even though I'm getting pretty good at it, here's to hoping I don't have to open one of these things up ever again: I sure wish I had a source for the internal rubber parts that wasn't simply to buy a "rebuilt" unit. I know they're putting new rubber parts in the rebuilds, so I know they're available. Just not available to me without buying a whole unit!

Not sure why, but the early service manuals didn't include the HVAC stuff on the wiring diagrams. From what I can tell, they didn't put the HVAC system on the wiring diagrams until 1974 for the 260. However, I believe I found some reference to the wire in question in a document titled "S30 Supplement Chassis Manual", and that wire is exactly what you thought it is... Power to the blower motor. That's the high side supply, and then the speeds are controlled by grounding the other side of the motor through one of the speed limiting resistors. Here's a link (I think this will work), to a copy of the document in which I found the info. It's not on the wiring diagrams, but they do mention it in a few of the harness descriptions. Take a look at page 2, and again on pages 26-27: http://www.classiczcars.com/applications/core/interface/file/attachment.php?id=65628

In theory, the amplitude of the reluctor coil pickup should be proportional to the speed of rotation. The faster you change the field, the higher the pulse amplitude. With that in mind... Was the missing issue only at idle? I would expect the pulse height to be plenty high once the RPM's are up. Also, I assume you checked the pickup gap was within spec, but someone has to ask.

Cool, and good luck with the project! You know your user name is wrong now, don't ya?

Clock can be tested just by connecting to 12V and see if it keeps time. Voltmeter you can just hook directly up to a variable voltage source. Should read volts just like any other voltmeter. Fuel gauge can be tested using a different resistor values or a potentiometer. Here's a thread with some additional info: http://www.classiczcars.com/topic/55746-fuel-gauge-accuracy-1975-280z/#comment-499020 As for temp gauge and oil pressure gauges, I haven't tested them, but I assume they operate just like the fuel gauge and should be able to be tested in the same manner. Maybe different sender resistance values, but other than that, I expect it to be the same concept. I have no experience with the ammeter, but if you have a variable voltage source with an adjustable current limit, you can crank the current limit way down and just start trying pins. If you keep the current low enough, you shouldn't hurt anything. Try configurations until you find one that works? And it could probably go without saying, but on all these tests, make sure you get the polarity correct.

I bet that's about right. Late 76 build. Sloped rear deck, and titled (at least it should be) as a 77.

What's the build date on the door jamb plate?

Haha!! You know, right after posted the claim about 77, I was thinking the exact same thing and was thinking someone may bring that up! However, looking at the pic of the engine compartment, it appears to have the 77 PCV hose routing, so barring higher res pics of the engine, I (got lucky and) stand by the claim of 77.

"Back Pressure Transducer". Part of the EGR system. I think the first year for said device was 77. I do not believe they were included in 76.

I'm trying right now (folding arms and blinking)...... Did it work? (Wiggling nose)...... How about now?

At quick glance, the reasons I'm calling it a 77 instead of a 76: Door latch design. Bumper designs (including the metal trim strips between the bumper and the body) It has a BPT.

Hahaha!!!

Welcome aboard! Let me help you out by making your car one year newer. Poof!! It's now a 77, not a 76. My work here is done.

I would definitely add a ball valve like you pictured in the engine compartment. You could probably keep it completely closed for most of the year and only need to crack it open at the very beginning and end of the season. Speaking of which... I could probably close mine down now. I don't think I'll be needing heat until maybe October. As for the capacity of the heater core, I haven't measured it, but I don't think it's even as much as a half gallon. Maybe between a quart and a half gallon?

Very nice! Wish I could have been there to see it run for the first time!!

I've been out of town off-line and am coming late to the party, but glad to hear that the project is complete. Working under that dash is a royal PITA. In fact, I've done it both ways and have actually found it to be worth the time to just pull the entire dash out to work on the heater system. As for which side of the heater core the valve is on, I don't think it really matters, especially if you use one of the newer style ball valves that Sweaty and I used. The original style valve is more affected by flow direction than a ball valve since it could theoretically be forced open by pressure of the water pump, but I wouldn't worry about any of the direction stuff at all with a ball valve.