FastWoman

It's a long shot, but the front-most bolt of the thermostat housing threads into a through-hole that enters the timing chain area right behind the guide/tensioner. Vacuum in the engine vs. pressure in the coolant system... bad thermo housing gasket, perhaps a crack somewhere... Who knows?

Here's a nice page about HEI retrofits for Mopar slant 6 engines: Slant Six Forum, :: View topic - HEI Electronic Ignition Retrofit How-To I haven't thoroughly digested it, but they do note the importance of a good ground, and they suggest a relay to provide good power to the unit. They discuss coil options and recommend a coil like Zed Head shows. Apparently they think quite highly of the HEI. Following the links, it is suggested that GM put some really great engineering into the module back in the early days of catalytic converters, because they didn't want misfires to melt down their already frail and junky converters, resulting potentially in fires from white-hot escaped catalyst pellets. I think there might be a few different versions of the HEI with different performance specifications -- different RPM ratings and dwell angles. I got the common variety of 4-pin unit, and it works fine. I don't rev my engine that high anyway -- probably 5k max. Something to keep in mind is that an 8 cylinder engine has more sparks per revolution than a 6 cylinder engine, so if an HEI made for an 8 cylinder engine is rated at 5500 RPM, hypothetically, it would be good for 7333 RPM in on a 6 cylinder engine.

I think that might have already been done! No distributor. Coil packs with lost spark? Coil on plug? Note the custom configuration of the radiator, so that the top radiator hose would line up perfectly between the radiator and thermo housing. Not practical when the engine rocks, but definitely pretty. Everything is stripped off the fenders, including relays, fusible links (is it a 280?), canister, washer, voltage regulator, etc., etc. Very pretty.

Your TPS doesn't care about RPM. It only cares about throttle position. It's your ECU that cares about RPM in relation to the TPS signal. Your RPM can be quite high without much throttle when not under load. However, what you've learned is that you can give the engine enough throttle when not under load to reach 3500 RPM before even breaking the low idle contact in the TPS, hence your problem. When properly adjusted, that contact should break when you just start opening the throttle. It should be closed only when your foot is off the pedal. As I recall, the TPS closes in the other direction at something like 3/4 or 2/3 throttle. Of course to adjust the TPS correctly, just rotate it and set it in the correct position with the little set screw.

It's a simple switch. Take off the cover, and give it a look. See if anything looks out of sorts. And don't worry; there aren't any exploding springs or bits that fall out!

Lenny, your idea of tightening the clock spring a tad for expanding the upper end of airflow metering might work, except you have to be mindful that the earlier 280 models have the fuel pump cutoff switch in their AFM. If the AFM vane does not hover open far enough, the fuel pump can cut off. Apparently this is already a tedious little dance with some Z owners. I love that the Hellfire will be such a powerful diagnostic tool. I hadn't even considered that. On that subject, you say you can "easily" tell whether injectors are delivering fuel (and/or whether there is problem with a cylinder?). I presume you would do this by selectively disabling individual injectors and measuring the effects on RPM. Yes?

Oops! Sorry Philip! I glanced up, saw the name beneath the quote (John Rushkin), and thus it was registered in my oft too flighty brain.

Hi Lennyclaus I think it's true we have very little idea what the true tension should be on the clock spring. Someone had to wind up the things and calibrate them on the assembly line back in the late 70's. I wonder whether the calibration specs/procedures could be obtained from Nissan. Hmmmm... I wonder whether Mr. K could be the conduit for this information? Absent any useful info from Nissan, here's my take on the AFM, and this comes down to speculation and opinion. (I think Blue and I might disagree somewhat on some of the details.) Firstly, Blue (John) measured a couple of AFMs that he believed were unmolested and came up with a spring calibration procedure here: http://atlanticz.ca/zclub/techtips/afm/calibration/index.html. We can only guess what has happened to these springs over time. They are surely weakened, but by how much? And are they simply deformed, or has their spring constant changed? I'm sure it's a some combination. However, assuming this calibration is correct, it could become the closest thing we have to a gold standard, unless someone somewhere has a better AFM, perhaps a NOS unit, from which we could take measurements. I'm not confident that a refurb AFM is really calibrated any better, using any more "correct" standards, than what could be done with the AltlanticZ method. And you may say none of this matters, but this is where I disagree somewhat, and I think this is where John and I disagree. During high'ish RPM (maybe 4500'ish?), WOT operation, the AFM will supposedly open fully ("pegging out"). Perhaps there is some enrichment function as RPMs continue to increase. I haven't found any useful info as to how this might happen, and I think this is where we get into mysterious territory. Perhaps John knows something I don't. Anyway, it seems to me that the AFM will peg out at an "incorrect" airflow rate with the wrong spring tension. For instance, if a system is enriched by loosening the clock spring, the AFM will peg out prematurely, possibly resulting in a lean mixture at high RPMs. So I think it's important to have the right spring tension. My thesis has always been that the ECUs, being analog devices operating under severe thermal conditions, have drifted over the decades, apparently towards shorter injector pulse widths. The correct compensation for the leaner condition is then to widen the pulse width at the ECU, and the best way to do that is by adding resistance to the CTS circuit. I disagree with the approach of loosening the clock spring, not only because of the AFM pegging out too soon, but also because the clock spring, if anything, is probably ALREADY looser because of the ravages of time and use. Anyway, my suggestion is to adopt some sort of gold standard for clock spring calibration. John's is probably the best we have. For the Hellfire to work properly out of the box with an OEM configuration, I think it is essential for the user to ensure at the very least that the fuel pressure is right, the CTS resistance is right, the AFM's potentiometer is functioning to spec, and the AFM's clock spring is calibrated to John's spec. As you say, these AFMs are all over the place now, mostly because of ham fisted adjustments by previous owners and/or their mechanics. Anyway, that's my 2c.

Very impressive! So will I have it in my Xmas stocking on the morning of the 25th? Hmmmm???? That's a nice method you have of cross-referencing the AFM output to actual airflow. Dumb question: Have you confirmed the spring calibration is correct on your AFM? I think I'm going to pop a champagne cork when you have your Hellfire board running your Z! The anticipation is too much!

I used to own a very nice little Z3. Awesome engine, somewhat weak body (for that engine), and really complicated and expensive to repair. After the failure of a steering angle sensor ($700), I decided a 280Z (my most loved car) would be much cheaper to keep in repair, even as an antique. In fact I decided it would be much cheaper than most modern cars, and I think I was right. So I sold the Z3, bought the 280Z, and I haven't looked back. One thing that attracts me to both cars is the inline 6 engine -- the only configuration besides a V12 that has perfect primary and secondary balance. The 280Z is a pleasure to work on, as long as the bolts aren't corroded in place. I think you'll enjoy owning one. Common issues: The fuel injected 280Z is going to run far more reliably than a carbureted 240 or 260 when in good repair. However, you are not likely to find a 280 in good repair. It might look pretty, but the EFI will almost certainly need a good going over. The good news is that it's not a particularly complicated EFI, and the parts are relatively cheap. However, the bad news is that the ECU on the later models (especially '78) seems to drift leaner over the years. (It's an analog device.) There's some help coming over the hill, though. Superlen is currently developing a plug&play digital ECU for the 280 that is upgradable with the engine. We're all very excited about it. Meanwhile, there are fixes for this issue, and you should be able to get your 280 to run as well as it did back in the day. Of course the carbureted models also have their issues, about which I know relatively little, but a company called ZTherapy will be able to help. All the Z models have pretty awful timing advance mechanisms. They commonly stick in place.

Thanks, guys!

Twas the night before Christmas and all through the shop, Not an injector was firing, not even a pop! The harness was strung on the engine with care, With hopes that a HellFire would soon be there. The gearheads were nestled all snug in their beds, While mixtures and power curves danced in their heads. And my Z beneath its cover in the garage warm and neat Had just been stowed for a long winter's retreat. When out on the road there arose such a clatter, I sprang from the bed to see what was the matter. Away to the window I flew like a flash, Tore open the shutters and threw up the sash. The moon on the breast of the new-fallen snow Gave the lustre of mid-day to objects below. When, what to my wondering eyes should appear, But a red Mustang Cobra blowing smoke out its rear. With a teenage driver shouting words I can't repeat, I knew in a moment it was that kid up the street. He taunted me loudly and called me by name, Yelling, "Bring out your Z, so feeble and lame!" I hung my head low, knowing she'd barely even start. If only I had that one magical part, A part that would bring new life to my ride, A part that would free the tiger inside! And then, in a twinkling, I heard on the roof The prancing and pawing of many a hoof. As I drew in my head, and was turning around, Down the chimney Lennyclaus came with a bound. He was dressed all in fur, from his head to his foot, And his clothes were all tarnished with grease and soot. A bundle of Hellfires he had flung on his back, And he looked like a peddler, just opening his pack. He spoke not a word, but went straight to the Z, Uncovering her lovingly and gently as could be. Before long he'd done what he came here to do. He upgraded my Z with a new ECU. Then he exclaimed with a chuckle, "I'll make you a wager." "I bet you can show up that obnoxious teenager!" And laying his finger aside of his nose, And giving a nod, up the chimney he rose! He sprang to his sleigh, to his team gave a whistle, And away they all flew like the down of a thistle. But I heard him exclaim, ‘ere he drove out of sight, "Happy Christmas to all, and to all a good-night!"

I agree with Chas! A gauge on that plugged inlet would be quite elegant. As long as you've got the wrong part, why not make it look like it was substituted for a reason?

Also the solid state flashers create less current load on your old wiring and switches. Even if you don't go with LED lights, they'll improve your situation.

Congratulations, Jan -- both for the job and for your forthcoming relocation to a more genteel locale.

I also note in your last photo that your wiring harness is unwrapped at the bullet connectors where the thermostat housing sensors tie in. Either mice chewed the wrapping off (not likely), or a human did it. Either way, it's a place to look for issues. One possible issue is that you have a bad connection to the coolant temp sensor, which seems to be the single, most common culprit for rich running. The best thing you can do is to go through all the EFI checks in the FSM. You perform these checks from the huge ECU connector beneath the driver kick panel. All you need is a multimeter, the FSM, and some patience.

Yes, the FPR looks fine. Mine is a '78, so I didn't know about the extra inlet in the earlier models. (I'm afraid my '75 is but a distant memory from an earlier life.) I do see your EGR equipment is missing, and you have a BPT valve control tube hanging open. It's the small metal tube ending almost dead-center in your 4th photo. I suspect exhaust leaks through the tube. This wouldn't keep your engine from running properly, but it could be a source of carbon monoxide in the cabin.

Well, if you can crawl into the hatch, remove the trim panel. That should give you access to the hatch lock. It unlocks by pushing the button. When you turn the key, the cylinder turns, and a tab aligns with a button/lever that operates the latch. Maybe you can reverse engineer it with that description. Then remove the thing, take it to a locksmith, and have it re-keyed. Just a guess: Maybe the hatch key is the same as the glove box key. So if a locksmith can "read" the code in the hatch lock, he can cut a key that would open the glove box (and then re-key the glove box). Stronger brakes: Rebuild! Brakes are usually weak because of rusted, frozen parts, air/moisture in the lines, etc. You should take it all apart, and rebuild it. Dash lights: Try cleaning the dimmer rheostat, or at least working the knob back and forth, back and forth.

Yes, Virginia, there IS a Lennyclaus! I think a woodworking project for a future Christmas will be a genuine curly maple steering wheel and shift knob. I've already got the carcass of an old rubber wheel I bought for $1 + S&H off of Ebay. The rubber was literally falling off it, and the seller wanted $50. I asked him if he would take $20, and he said "no." When his auction ended with no bids, I again offered him $20, and he relisted for the starting price of a buck, so that I would bid on it. I guess he expected to get $50 for it at the tail end of a bidding frenzy, but he got a buck.

Maybe a Superlen Zfuel Hellfire ECU??? Or maybe just the promise of one.

I don't think there's $450 in usable parts. What's the spot price of scrap steel these days?

Jan, although clutch chatter isn't generally attributed to overheating and excessive glaze buildup on the flywheel, I think this is possibly the most common cause. At least it seems to be in my household (3 stick and 1 auto). My Saturn SL2's transmission is the best I've ever driven -- smooth and intuitive for over 2 decades until I replaced the worn, slipping clutch. The new clutch broke in well and felt just as perfect as the first. However, after a few months of hard driving by my stepson, it came back with a bit of a chatter. The most common/persistent shifting error seems to be riding the clutch when shifting from 2-5, as though starting from a dead stop. Totally unnecessary. Another of our vehicles had an oil leak into the bell housing (CAS O-ring failure), and that has resulted in a chatter as well.

If you have anything blocked off on your FPR, then you have a problem. I'm guessing your return line is blocked off, and the fuel rail is running at the full output pressure of the fuel pump, which would be in the neighborhood of 45 psi. Instead, it should be running in the neighborhood of 30 psi. Higher pressure means too much fuel injected. That's likely why your engine is choking -- or at least one of the reasons. Take a look at where your steel fuel lines enter the engine compartment from under the car on the passenger side. One of them will go to the fuel filter and is your supply line. There should be another one right next to it. I bet it's blocked off. There should be a fuel line between the fuel pressure regulator and that steel line to carry return flow back to the tank. Before hooking it up, blow some air through it to make certain it's not blocked with rust and debris. If it's blocked, you'll still have the same fuel pressure problem. I agree with Euro: A picture would tell us a lot.

It's more likely the mice chewed some of your wiring. I'd look for that first. BTW, be very careful with any mouse poop you find. Mice can carry the hantavirus, which is deadly. Wear a mask, wash your hands, and shower after handling mouse debris.

Hey, I own two of the five! Well, sort of. I've got the Miata NA and a 280. (He said 240 or even a 260. What's he got against fuel injection?)