FastWoman

I think the discussion starts around post #57 of my "purs like a kitten" thread (page 3): http://www.classiczcars.com/forums/showthread.php?t=40234&page=3 I don't have a well developed calibration method, though. I suppose I'd really need a dyno to do it right, but that's beyond my means or level of seriousness. I currently err very slightly on the rich side - "old school" conservatism. I'd shoot for a bit leaner if I had a cat.

I agree the 1st gen Miata is a recent classic. We're in the market for one, and I've become active with that community. I'm amazed at the by the abundant support and enthusiasm behind that automobile. IMO, the 64.5 Mustang, '67 Camaro, '57 T-Bird, etc., etc. are all classic cars AND have reached antique status. The same is true of our S30 Z's. I would hope the Wikipedia article isn't implying that antique status and classic status are somehow mutually exclusive. That would be awfully near-sighted. Taken at face value, it's almost implies that an antique is so old as not to make anyone's heart race just a bit. Many of the Duesenbergs, Cords, Auburns, and others clearly sock the wind out of that notion. I also take issue with the age criterion of 45 years. Who ever came up with that?! Most states (?) agree that a car becomes an antique at age 25 and are therefore subject to different rules and regs, can wear antique tags, etc. That seems to be a pretty good age criterion, as it is an age beyond which few cars survive without considerable restorative efforts. Anyway, to me a 1st gen Z is an antique classic. A 1982 Datsun 210 is an antique but not a classic (because it wasn't particularly special). A 1st gen Miata is a classic and not an antique. And a Chevy Cobalt isn't much of anything.

I've never tuned SU carbs, but I've read a bit about tuning the Zenith Strombergs. They suggest a method for balancing the carbs that only takes a short length of rubber tubing. Just put one end of the tube to your ear, and hold the other end to the mouth of each carb. Adjust your throttle plate so that the hiss is equally loud from each carb. It might not be as accurate as with a flow meter, but it'll probably get you down the road until you get one.

I think there are other factors besides age. I personally feel that a classic often represents some important development or niche in the automotive industry, so yes, a Ford Pinto might in some respects be a classic. For better or worse, it defined certain aspects of a bygone era. I have to admit a beat-up Pinto I saw at the gas pump several years back brought quite a smile to my face. Were they great cars? By no means! But they were important to the era. Whether someone would want to go through the work and expense of restoring a derelict Pinto is another matter. (A critical piece of a stock restoration would probably be that fatal U-bolt that made the cars go kaboom!) Very few people would take on such a project. I know I wouldn't. Oddly, that makes road-worthy Pintos quite rare. Smile, because there are still rare people who might keep a few of these cars on the road... http://cgi.ebay.com/ebaymotors/Ford-Pinto-1971-Pinto-Survivor-/160511857676?pt=US_Cars_Trucks&hash=item255f40940c

Doesn't your 1972 240 have points ignition? Check that the (+) post of your coil gets 12V when you turn on the ignition. Disconnect the wires from the (-) side of the coil, and measure the resistance between those wires and ground, while you crank the engine. You should see the resistance alternating between zero and infinity (pretty sure about this). If not, there's probably a problem with your points, condenser, or wiring from the distributor to the coil. With the wires still off the (-) post, measure the resistance between the (-) and (+) posts of the coil. Resistance shouldn't be infinite, and it shouldn't be zero-ish. (I don't know what a normal resistance would be.) Points ignitions aren't really my thing, but that might get you started.

I don't know the anatomy of an SU very well, but if you're dealing with a rough part, you can always polish it. Hand rubbing with rubbing compound (i.e. for paint) works fine in a pinch.

dual carbs, triple carbs, or one 1-barrel carb on each of the 6 (or perhaps I'm imagining having seen that one once)

Jenny, you can think of the engine vacuum as a reflection of the efficiency at which your engine is running. No running = no vacuum. Efficient running at the right mix = about 19" vacuum. The faster your engine runs on a little bit of air, the more vacuum it's going to pull, because it's essentially behaving like a vacuum pump. Anyway, all a low vacuum means in your case is that the engine is running too rich or lean (in your case too lean). So in direct answer to your question, it's the low idle causing the low vacuum -- sort of. However, if you raise the idle, you'll still have a low vacuum because you're introducing more air and still running ineffeciently. Carbon canister: It probably won't make a huge difference either way. I'd leave it connected. Just make sure it's not a source of vacuum leakage. (The only real vacuum line is the little hose to the cap.) Could faulty spark plugs cause low engine vacuum? Yes. Anything that decreases engine efficiency will lower the vacuum. However, it's probably not your root cause. That said, you could have fouling spark plugs due to misfires (like I did), but the spark plugs would be a secondary issue. I doubt you have spark plug issues. The PVC valve: You need to have that connected, or else you'll have a huge vacuum leak out the top of the valve cover and into the throttle body. PCV valves are very cheap and plentiful, BTW. It's probably not a bad idea to install a new one. It unscrews from the bottom of the intake manifold. BTW, I don't think you'll end up ejecting any hot oil out the PCV hose, and don't worry about oil on the paint (which will wipe off and won't do any damage). However, you don't want the vacuum leak. Throttle body jumper: Just use a wire. Any wire will do. You can even use a twist tie with the ends stripped bare. Just make sure you make good electrical contact and don't touch the wire to any other metal parts. The TPS: It's just a switch. There's a little spring arm that fits into the wiggly track. When the throttle is closed, the middle arm is pushed against one contact. Opening up slightly, the arm moves to the middle and doesn't touch either contact. At higher throttle, the arm is pushed over to touch the other contact. You would introduce a jumper between the wires connecting to the middle arm and the second (higher throttle) contact. Goodyear EZ Coil: This is a stainless steel slinky-like product you can fit over the 5/8" hose to put a 90 deg bend in it without it collapsing. You can also just do a sloppy, sweeping bend in the hose. I hate the way the hose looks, so I made a pipe out of 1/2" copper pipe and elbows from Lowes: Hatch rust: Congratulations! I have some rust there I have to address. Not fun. Spring project. Distributor advance: He was probably talking about how the breaker plate freezes up inside the stock distributor. Take off the distributor cap and rotor, and you'll see a magnetic, star-shaped cam (for lack of a better word) and a coil beside it. The coil is fastened to a metal plate. The plate should rotate to the right (?) under high engine vacuum. Most Z plates won't rotate at all and are frozen/rusted in place. Give it a twist with your hand to see if it moves. Then try moving the plate under vacuum. If you can suck pretty hard, you can just attach a tube to the vacuum advance and suck away. The breaker plate should rotate. If it doesn't, your vacuum advance doesn't work. The cheapest/easiest fix is to pick up a rebuilt distributor from AutoZone -- about $100, lifetime warranted, which is a good deal for this troublesome part. You'll need to take them your old one to be rebuilt for someone else (and to get your core charge back). Make sure the cam at the end of the shaft doesn't wobble. Sometimes they bend that shaft when they rebuild it. The distributor lifts out after you completely remove the bolt you loosen to adjust your timing. I believe you also have to transfer the base plate to the new distributor. (I'm describing all this, BTW, because your distributor is more likely bad than good. I understand most are bad.) Phew! You've got your work cut out for you!

BTW, another factor here is that people have different standards for old engines/cars than for new ones. They expect them to run worse with the passage of time. Even professional mechanics share this expectation, strangely. When there's an "annoying" engine light that won't go away, it never occurs to the mechanic that there might actually be a problem that has eluded diagnosis. It's just dismissed as "fussiness," and the light is reset. That happened with several of the PO's dealer service experiences with my Z3. The problem was a crack in the intake boot between the AFM and throttle body, a coolant sensor out of spec, and lots of varnish in the valve train. After I corrected that, it purred like a kitten. Same with my 280Z. The local Z guy thought my engine was running well, but it didn't really run well until I fixed a substantial intake leak (replacing the manifold gasket), replaced a stuck (open) cold start injector, replaced all of the regular injectors, replaced a bad coolant temp sensor, replaced all of my electrical connectors (some of which weren't connecting), and calibrated my mix with the resistor in series with the coolant temp sensor. NOW my engine runs great. Next engine -- my '92 Saturn SL-2, basically not much done to it since I bought it in '91, aside from plugs and wires. Everyone thinks it runs great (for an old car). However, it hesitates in the cold, and the exhaust doesn't smell right. Next spring I'll be replacing the injectors, testing the sensors, probably replacing the O2 sensor, definitely cleaning the little hot wire (!), and whatever it takes to put it right. There's potential for a flawlessly running engine in there, and I know something's not right. I don't know why people think old engines have to run badly, but they do. Strange.

Zed Head, I get what you mean, and I've briefly wondered that myself. However, engine vacuum is a pretty good and objective metric of engine operating efficiency. When an engine is running at 19 in Hg at idle, it's got a good mixture going, and it's hitting on all 6 pretty smoothly and cleanly. When it's pulling 14 in Hg, it's probably either too rich or too lean, or something else is going on that shouldn't, and it's not running so well. That hasn't changed over the decades. In fact I'm still using a vacuum gauge that is older than my car, and its scale has green zone painted on it that indicates a "normal" cutoff of 18 in Hg, so nothing has changed. My gauge is still accurate too, as it indicates vacuum in the "green" 18-21 in Hg zone for modern engines, such as the inline 6 3.0L VVT on the Z3 I recently fixed up. (NICE engine! ) I do think the E10 issue has some merit, especially since our E10 is really sometimes E20 or E30 by the time we're able to pump it into our tanks. (Everyone likes to harvest those tax incentives, even when it's illegal to do so, and they don't care what it does to our cars.) Of course as you point out, there's less energy per volume of E10/20/30 than there was in our wonderful E-ZERO, so old engines on modern gas run a bit leaner when delivering the same fuel volume per unit air volume. That said, the differences aren't really all that great. I think they impact our open loop EFI more than a closed loop EFI or carb system, because the latter two systems have adjustment capabilities, and the open loop EFI doesn't (ordinarily). Even so, it's not all that big a difference. By comparison, the mix problems Coz and I were experiencing were huge. He described his. Mine were similar, except that I could maintain an idle. My exhaust would blow and puff, and I had occasional backfires (which would never happen with a properly running street engine). These were things that didn't happen with my engines back in the day. My memory may have drifted as to how smooth our engines were, but it hasn't drifted as to issues of engine vacuum and backfiring. To put the problem into perspective, another final adjustment I considered for the mixture problem was to run a higher fuel pressure by changing out the FPR. I thought I might be able to even out my mix by bumping the pressure a few psi. To test this idea, I pulled the vacuum hose to the FPR at idle and got some improvement in running. I then applied air pressure to the FPR as a "boost" and was able to drive the differential between fuel pressure and manifold vacuum as high as 50 psi, limited by my fuel pump. The engine ran much smoother but wanted a bit more fuel still. I think I was pulling a vacuum of 17 then. I'm guessing I might have achieved the right mix at 60 or 65 psi if I could go that far. Of course roughly double the pressure doesn't mean roughly double the fuel, as I don't know where Reynolds numbers start kicking in. However, I think I can safely say that double the fuel pressure is a LOT more fuel and that the abnormalities in my mix were quite substantial. Anyway, as Coz points out, we're re-discovered what the old-timers already knew and reinvented the fix for the problem. Of course I AM an old-timer when it comes to electronics, having worked with every generation of electronics to present. (I still have my tube tester and a maybe 40 lb box of spare tubes!) I already knew that semiconductors break down over time, particularly the early ones if oil leaks out of the little can. For me, electronics wasn't about making a radio or TV work. It was about high precision instrumentation that had to be dead-on accurate. (I was formerly a scientist, before research funding went the way of the dodo.) So when a component drifted, I KNEW it. In fact I had a practice of socketing all of my linear semiconductors (both transistors and ICs) so that I could easily replace them when they went out of spec. ICs were of course very robust, but they would sometimes lose some of their output voltage range, pegging out farther and farther from the supply rail voltages. Transistors would mostly lose gain. The degradation of electronic components over time is well known and widely discussed. Semiconductors break down from heat and the passage of time. Holes migrate and cluster. Junctions weaken, and metals migrate. Not even digital circuitry is immune. Ever notice how a computer runs hotter and hotter as it ages, until one day you get the blue screen of death? Anyway, our ECUs take a lot of punishment, not the least of which is being operated with poor ventilation in a car that's just baked in the sun for 5 hours. It's perhaps a wonder they still operate at all.

Anyway, if you don't believe in my little mod, don't use it. There, that was simple.

The motor is within specs -- 165-172 dry compression, 13 deg BTDC timing (10 deg works almost as well), valve timing still within #1 hole range, valve lash is right. Absolutely NO leaks anywhere. All sensors are to spec, including the AFM. I pull a more or less normal vacuum now (18.5 in Hg). I'm sure if I had a fresh engine I'd pull higher. Combined mileage is 21 mpg. Acceleration is brisk. Plugs are clean, with a hint of mocha, but not chalky. Exhaust is clean. Motor sounds good. Idle is smooooth and easy. Runs like my '75 did back in '83 after I got it straightened out. ... but feel free to disagree. What do I know? :stupid:

Powerglide, Cozye and I have just been through the mill on this issue. Both of us have restored our intake/fuel systems to rock-solid, within OEM specs status. Mine might even be more so, as I redid my entire system from the fuel tank to the injector, including completely new injectors and electrical connectors. We've both found that both of our ECUs ran our engines quite lean -- lean enough to create backfire and a vacuum of 14 or 15 in Hg, but not lean enough to keep my local Z specialist from commenting that my engine ran well (go figure!). In addition, my spare ECU ran the engine just as lean. The fix for both of us was resistors in series with the coolant temp sensor, which lengthened the output pulse proportionally at all delivery levels. In my case, the needed resistance was substantial -- about 2.4 kOhms. According to Cozye, who has researched the issue far more than I have, this is a known issue with our ECUs and a very common fix. So yes, these black boxes do drift. Semiconductors do break down and lose both gain and linearity. I've refurbed enough early hybrid tube/solid state oscilloscopes (similar generation of component solid state electronics) to have seen this with some predictability and regularity. They're not all linear ICs in the ECU, BTW. There's a lot of plain vanilla component transistor circuitry as well. It's impossible to know much about these circuits without schematics and components data, and as such, they would be really hard to service. One might be able to replace some of the 1st gen oil-canned transistors (of unknown identity), for instance, but at what current gain? Forget replacing the ICs, except with little daughter boards. They are canned in oil, like the transistors -- first I've ever seen packaged like that. You won't find THOSE anywhere. I think when our boards finally start dying, we're going to have to switch over to Megasquirt/Microsquirt retrofits. I think it'd be great if someone figured out a Microsquirt retrofit for a plug and play ECU -- i.e. by retrofitting the board in the stock box, with the stock connections and program suitable for the 280Z. It's my understanding that these systems can run on the old vane AFMs and w/o O2 sensor.

Yeah, basically stock -- just not OEM Nissan. If I were you, I think I'd try stock injectors [EDIT: AND AFM) as a first stab at the problem. Forget about the cam, throttle body, and 100 psi pump for now. I don't think those are going to affect your mix. Just leave 'em and see what happens. (But of course verify your fuel pressure to make certain the pump isn't too much!) If you want to consider Megasquirt, you can probably cobble a MAP to the intake and an O2 sensor to the exhaust. (A muffler shop should be able to weld a fitting into your exhaust for the sensor.) I suppose the route you take depends a bit on what you want to do with the car. If you just want to drive it, the easiest route would probably be to revert to stock. If you want to race it, then you may want to keep the mods. The stock injectors might not put out enough fuel to keep up with the cam at high RPMs and WOT. Your mixture might end up too lean, which definitely isn't good. In that case the injectors you have, controlled by a Megasquirt system, might be the better route.

Jan, there's dumb and dumber, so to speak. The early ECUs with linear circuitry and no lambda feedback are dumb, but carbs are dumber. Either can meter fuel rather accurately when in good repair. The problem is that both are subject to inaccuracies and become tempermental over time. Cozye and I have just discovered that our ECUs have drifted over time in their output properties and required rather strong corrections to the mix through the coolant temp circuit. My comment about "dumb" wasn't meant to be disparaging. I remember when I bought my '75 Z (not the one I currently own) in 1982. It was my first EFI car, and I thought it was the cat's pajamas! Even then (with an 8 year old car) the EFI was quite tempermental, but there was a certain magic about it that I loved. I also don't want to disparage linear circuitry too much, because I've designed and built so much of it. I suppose familiarity breeds contempt. I know how these sorts of circuits fail, and I understand what toll is exacted with time and usage. There is a HUGE difference between linear and digital control. Both have their respective strengths and weaknesses. However, a digital system will be very stable until it fails. The linear sensors are of course subject to deterioration and drift, but those are all individually serviceable. Ultimately the O2 sensor is the calibration point, so if all the sensors are within reasonable range, the engine will run very well. Anyway, the question was posed as to the purpose of such an exercise. My answer is that our ECUs are starting to degrade in very predictable ways that I've seen over and over again in multitudes of linear devices. They're elderly and probably nearing the end of their service life, even with bandaid patches like Cozye and I have used. And once these devices fail, they will not be repairable, owing to proprietary circuitry. (You are warned! ) Anyone interested in preserving the old hardware, rather than retrofitting with new technology, is faced with this reality. There is no absolute solution to this problem, but offloading power demands from the device is one possible way to delay the inevitable. Please note that the huge investment of time and money I'm proposing is probably 30 min and a few bucks in parts. To go totally nerdy on y'all, I see our Z's as examples of V-GER from the original Star Trek movie. They are humble devices that are patched, augmented and retrofitted to remain functional. But at their core is the same charming core device. I like preserving as much of that device as possible, or at least that's the way I feel about it at this stage in my life.

Carl, I don't think LED headlights would require headlight relays. The problem is that I don't think anyone makes LED headlights for our cars. I think Lexus has introduced LED headlights, but I think they're ahead of the curve. Almost on that subject, I've seen cheap LED driving lights at the auto parts store. Has anyone tried these? I wouldn't put them on my Z (kinda tacky, plasticky things), but they look great for boating -- particularly on our sailboat (where power budgets are very stingy).

That's one of my next projects -- LED conversion. It's a simple thing and will add so much life to our crusty electrical systems. About LED fade: Strictly speaking, LEDs don't really fade (much). They just keep cranking away until one day they fail. However, that's not true in practice with WHITE LEDs. White LEDs are really blue/near UV LEDs that are coated with phosphors. When the phosphors are hit with the higher energy near UV and blue light, they fluoresce at a variety of longer wavelengths, adding to the blue light that comes through the phosphors to create white light. Over time the phosphors degrade significantly, resulting in very dull light. So when you convert to LED bulbs, make sure to buy the ones that come in colors (e.g. amber or red) wherever possible. They'll keep their brightness very well, as compared to their white counterparts. OH, and flashers: The electronic ones are VERY cheap and easy to substitute. Both the turn signal and hazard flashers are under the dash (at least in my '78). I got generic electronic ones and made mounts for them out of PVC pipe. They sell load resistors to run LED lights with thermal flashers, but I don't know why anyone would want to go through the trouble/expense of LED conversion and then load the thermal flashers with power resistors -- except maybe to be kinder to the bulb sockets.

Kathy and Rick, I think you got the postings confused. I already have the louvers -- the sort that tucks under the weather seal. I'd never drill my hatch, though, at least for anything that shakes around in the wind! My first car was a '75 Celica with a cute little luggage rack on the trunk lid. That was always a leakage problem. Fortunately I lived in a very dry climate. But yes, I like having the louvers. I didn't think I would, and I considered taking them off when I bought the car, but they do work very well. I did take off the little plastic quarter window louvers, though. They looked cheap, obscured my view, and didn't do anything to help with the sun or glare. I thought they also broke up some of the more attractive lines of the car.

Bmuu, the pressure regulator does drop fuel pressure at high vacuum (e.g. at idle), but only because it is maintaining a constant pressure differential between the fuel rail and intake manifold. It's nothing more complicated than that. If you have a high engine vacuum and no compensation for that in the fuel pressure, then the gas is going to be sucked out of the injectors at a higher rate. All the regulator does is to keep the fuel delivery rate constant, so that the ECU can regulate delivery in terms of pulse width. I tend to agree with Jim and Coz (Eric). As your system is configured, you're probably going to have to go with a non-stock ECU, like a MegaSquirt system. Either that, or you're going to have to revert back to stock injectors. (I admittedly don't know what to expect from that cam on an EFI system.) FAIW, I'm running these right now, and they work fine: http://cgi.ebay.com/ebaymotors/75-76-77-78-79-80-81-82-83-Datsun-280Z-Fuel-Injectors-_W0QQcmdZViewItemQQhashZitem255f93698eQQitemZ160517286286QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories Important question, though: As far as you know, did the engine ever run correctly with this configuration, or was it a project gone wrong and sold cheaply to someone else? Knowing this answer will make all the difference in how you should approach correcting your current problem. Anyway, that's about the extent of the advice I can offer. If you want to keep the modified configuration, your best advice is probably going to come from the HybridZ forum, 'cuz they do that sort of stuff all the time.

Thanks, guys! It sounds about like our boat transmission in weight. Not fun, but I managed. (I farmed out the rebuild, though!) Anyway, I guess that's what I'll do, come spring. Meanwhile, I'm going to stay warm!

For the most part, what determines your fuel delivery is the air flow through the air flow meter, the readings of the other sensors (for fine tuning). The ECU does its computations based on these, and it delivers a pulse width to the injectors that is directly proportional to the amount of fuel to be delivered. If it's functioning properly, the fuel pressure regulator maintains a constant pressure differential between the fuel rail and the intake manifold. That constant differential results in a known delivery of fuel for a given pulse width. If your manifold vacuum is low, the pressure should regulate higher, so as to deliver that constant flow rate. Your system has so many mods that I wouldn't really know where to begin with it. However, the fact that the injectors are "high flow/pressure injectors" suggests to me that their flow rate is foreign to the ECU. I think that's a huge potential problem, and you should verify that the injectors deliver fuel at a roughly ordinary rate when switched on. Before you invest lots of time in pursuing that avenue, however, I'd check the connection to the coolant temperature sensor. If you have a bad connection there (or a bad/open sensor), you'll experience EXTREMELY rich running -- black smoke out the tail pipe, very bad idle, etc. -- just as you've described. Those electrical connectors get pretty crumbly, especially on the front of the engine. I think you would learn the most by pulling the connector off of your ECU (and not touching the temp sensor yet). Measure for conductivity between pin 13 and ground. It should be in the neighborhood of a couple of kohms cold, give or take, depending on temperature. If you read an open circuit, there's your problem. You'll probably need to clean up the connector to the water temp sensor (the smaller of the sensors in your thermo housing with two wires -- not the one with the single wire). The other place I'd look is your cold start valve. It might be stuck open, or the thermotime switch (the other two-wire plug in the thermo housing) might be having issues. Anyway, I really doubt the radical cam is to blame for the rich running. The pump may be rather high pressure, but I suspect the fuel pressure regulator can handle it. (Just measure the fuel pressure to be certain!) As far as you know, did the modified engine ever run right?

Thanks, Al, but isn't fiddling with the oils just a way of buying time? With a leaky front seal, 165k on the original clutch, and synchronizers that are that fussy, am I not at a point where I really need to pull the stuff out and rebuild it anyway? I'm not planning to do it tomorrow, mind you, but I think it might be a spring project, whether I do it myself or farm it out. (I'm leaning more towards attempting it myself.)

That would make it a pretty cold, dry day in Houston!

Well, it sounds worth considering. About how much does a 5 speed weigh, give or take? And about how much time should I budget myself for a transmission and clutch rebuild? Tlorber, I appreciate the kind offer of your vice frame. I might take you up on it yet.

Scott, I did a relay conversion on my '78. The relays fit very nicely inside the relay box where the fusible link housings are attached. The wiring dropped down into the large harness below. You wouldn't know it's there. Details are buried somewhere in this thread: http://www.classiczcars.com/forums/showthread.php?t=35588&highlight=breakers