FastWoman

Argneist, are you SUUUURE you were at the "correct" TDC on each cylinder? You see, the engine rotates twice per cycle. The cycle starts at what might look like TDC, when the exhaust valve closes and the intake valve opens. Then the piston moves down to draw in fuel/air. Then both valves are closed, and the compression stroke begins. Then the piston moves up as the engine rotates to the "REAL" TDC (the one that really counts). That's approx. where the spark would fire. The next stroke is the power stroke, where the piston moves down and applies force to the crankshaft. Then there's the exhaust stroke, where the exhaust valve opens and the piston moves up to expel the exhaust gasses. That takes us back to where we began. If you want to be sure you're on the correct part of the cycle, you can confirm by removing the distributor cap and observing that the rotor is pointing to the wire position for the cylinder you're testing. I suspect your engine is fine. I suspect you were just testing 3 of your cylinders at the wrong points in their cycle.

What do your plugs look like? Can you post some pictures of the bottoms of your plugs?

Jenny, since I cleaned up and painted the top end of my engine, I think it's gained 50hp! I'm being facetious, of course, but people perceive that when they look at it. It's amazing how a bit of spit and polish can sell an engine, and people have much less attention to what's inside. So this guy is selling a very pretty engine, certainly! But how good is the rebuild work underneath? Are the parts of a high quality and well matched? Are the tolerances tight? Is the machine work well done? If I understand correctly, that's where this guy falls short. If/when you need your L28 rebuilt my advice would be to go to a local engine builder with a very solid reputation. I don't think the rebuilder needs special knowledge of the L28 unless it is to be used for racing. In that case, go to your local Z specialist, who might end up farming out the work to the local guy with the solid reputation. However, the Z person will know what mods work well and which ones don't. Otherwise, if it's for everyday street use, any GOOD rebuilder should be up for the job.

As far as I'm aware, you're not missing anything. Is this "an essential part for your restoration" (ala reddat)?

Jenny, it's useless and potentially a Pandora's box to mess with the head bolts. They're likely corroded, so torque will be irrelevant. The best case is that you do nothing useful. The worst case is that you snap a head bolt.

OK, I understand, and that's fine. You shouldn't do things that are past your comfort zone. Well, a year or so down the line, if you happen to have the thing off your car, and IF you're comfortable with it then, please shoot me a PM, and we'll work on a calibration procedure. The offer/request also stands for anyone else who has a "virgin" (or nearly "virgin") AFM. (Zed????)

A car without a catalytic converter will have some exhaust smell that may be what you call a "traditional smell." My '78 280Z has no catalytic converter (not a California model), and so it has a mild "traditional smell," even though it's fuel injected. It smells very much like my Edelbrock-carbureted '66 289 Mustang did. Any car with a catalytic converter will smell much cleaner. There's no reason you can't install a generic catalytic converter on your 260 if the smell bothers you that badly.

Mike -- Interesting. Ya' learn something new everyday.

Between the VR being wired wrongly to the plug and your car being wired wrongly, I'd place my bets on the car. After all, the PO had snipped off that black wire. That's not a proper fix and doesn't give me much confidence in anything else. I bet if you traced out the wiring from the VR connector, you'd find where it's spliced incorrectly into the wiring harness somewhere. I don't see any reason to go to the IR alternator. It shouldn't be too hard a job to trace out the wiring between the VR and the alternator and find where the PO had miswired it. It should be easy to fix your VR, just by soldering back the wire that burnt away.

Yea! Glad it was something simple!

SteveJ, FAIW, not all ammeter systems route the current through the ammeter. For instance, my '66 Mustang had a very creative ammeter system, in which a galvanometer was used to indicate voltage drop across an approx. 3 ft length of heavy wire. It lacked for accuracy and, in fact, was defunct in my car. (I never repaired it.) I've suggested to some people on this list who were upgrading the alternator wiring in their 240 that they could run a heavier line from the alt to a shunt to a fusible link to the battery, all beneath the hood. Then they could run two small-gauge wires off of the two sides of the shunt and to the ammeter, whose shunt had been removed. I further suggested that they could drill a hole in the middle of the shunt, attaching the wires to the middle and one end, to cut the shunt resistance in half and therefore reduce the full-scale sensitivity of the ammeter by roughly half. So ammeters don't need to be quite as clunky as they're currently wired. I'm with you, FAIW. I'd like to have both. However, of the two, a voltmeter seems to do me more good.

Yeah, looks like a ground point on the VR. The good news is that you wouldn't have damaged your new VR or any component of the charging system. You might need to reattach a black wire to run to ground, BUT... The black wire that burnt is apparently NOT a ground. It would have to be hot to burn when connected to a ground point. You've got something wired wrong. I suppose the ground wire would be redundant with a simple mechanical grounding of the VR to the chassis. I suspect the purpose of the wire is to make CERTAIN the VR is grounded, so as to avoid an overvoltage that might damage sensitive electronic systems. So I think it might be good to figure out the right ground.

I use B6ES-11 (non-resistive, non-projecting) and the spiral-wound wires. No noise problems here, although I don't listen to AM. I have a fairly nice sound system too. There's another reason to use the R plugs besides noise. Supposedly the spark duration is lengthened a bit, so that the entirety of the coil's energy isn't dumped immediately in a quick zap. However, the inductance of the wires does that anyway, as far as I'm aware. I just use what has a long history of working well. I don't get too worked up over tiny tweaks.

Leonard, when your voltmeter reads anywhere north of, say, 13v, your alternator is maintaining the charge. So if my voltmeter were to drop from its usual 14.5 to maybe a steady 12.5, irrespective of RPM, I'd know I was slowly discharging and that my alternator wasn't doing anything. Besides that, there's a little alternator fault light on the 280's voltmeter, and that will probably grab your attention faster than an ammeter needle.

Argneist, I told you to note the position first! (Don't worry. I did the same thing.) There's an alignment notch on the flange of the sender unit. You'll see. It won't fit completely flat without the notch being correctly aligned. You can look around the tank with a dental mirror and PROBABLY a well sealed (water tight) LED light. But don't use ANY light that might create any sort of spark!!!!!! Don't dare use anything with a breakable bulb!!!!! If you use a very clean mechanic's mirror (a bit larger than a dental mirror), you can bounce the flashlight off of the mirror to introduce the light into the tank, while still leaving yourself enough room to peer into the tank. A very bright keychain LED light works well for this. (You would hold the light right by your eye, pointing towards the mirror.) , As with ANY light, satisfy yourself as to any spark risk, because you don't want your tank to explode in your face!!! (Note: Gas fumes can explode too, even in an empty tank.) As your tank is mounted to the car, you might have to climb into your hatch to get your eye close enough to the hole to see much. Dunno. The rust is coming from somewhere. It might be your intake line. They can be prone to rust.

Here you go: http://www.autopartswarehouse.com/details/QQNissanQQ280ZQQNGKQQSpark_Plug_WireQQ19751978QQW0133-1625833.html

Bingo! Yes, your wires need replacement. I'm quite optimistic that will solve your problems. Just as I thought, your ignition was getting weak, and you were starting to get misfires on certain cylinders. I'll bet if you'll find the cleaner plugs gapped just a bit narrower than your dirty plugs. A spark had probably been gapping some distance inside the coil wire. Do yourself a favor, and use NGK's blue spiral-wound (inductive core) wires. In my experience, they'll last forever and give you a very nice spark. If you need resistance, put it in the plugs. NGK has resistive plugs for that. That said, I never found I needed resistance. The inductive reactance of the core does just fine. And yes, I'd run the engine at 180. The SeaFoam treatment I'm recommending isn't an oil flush. I'm suggesting you flush the intake and cylinders. There are procedures described here and there. Basically you dump a LOT of the stuff into your intake until it kills the engine. Then you let it soak. And then you blow it all out and change your oil. This will rid you of your heavy carbon deposits.

My HEI retrofit was only about $14.25 -- $14 for the HEI module, and 25 cents for the nice heat sink I bought (lots of 'em) back in the 80's.

I ordered a few parts from them. They seemed OK. That said, I wouldn't deal with them again without some means of contacting them. Stuff happens, and you certainly need some lines of communication. Unless it's something you can't find elsewhere, I'd write them off your list.

The '78 IM is behind the passenger kick panel. It's a black box that's a few inches by a few inches by about an inch. You can't miss it. Here's the HEI retrofit: http://zhome.com/ZCMnL/tech/gmhei.html I put one of these modules in my car and have been running it maybe a year. Works great. I put a heat sink on the back of the thing.

I had a different spring tension test in mind. I'm interested in the force required to just start opening the flap. I'm also interested in the voltage output at different flap opening distances, which you could determine by pulling the flap open with a string in perhaps 1 cm increments (e.g. marked on the string). No need to open the cover for any of that. Can I mail you the stuff you'd need for powering the thing up with a 9V battery and testing voltages? *9V battery *9V battery clip with alligator clips on the leads *a couple of test leads with alligator clips on their ends Just to be clear, the 9V battery isn't going to put out anywhere near enough current to hurt anything, even if you accidentally short your leads. I know you think the resistances are more important than the voltages, but if you could humor me on this test, I think we could put together some really good test/calibration procedures for use by the Z community. Among other things, you and I could use it to test/calibrate our spare AFMs. re your intuition about replacing the CTS before the AFM: Go with your gut!

Sorry for the thread hijack, but Carl, did the service bulletins recommend the projected tips for all models (e.g. my '78?) Thanks...

I think you're right, Diseased. I hadn't noticed that. That would certainly be consistent with lean running. Yikes! Jetaway, the crud stuck in your #3 plug would have been a dislodged chunk of carbon. You've got a really bad problem with incomplete burning. One hazard of this is that you'll throw chunk of carbon that lodge in the exhaust valve, resulting in burning of the valve and seat. You might want to give your engine a SeaFoam treatment to wash out the carbon. (And then do an oil change, of course.) I don't think your cruising in high gears is a problem, as long as you don't do it under power. I've gotten in the habit of dropping to higher gears myself whenever just maintaining a steady speed. I'll make a long run down a flat 35 mph road in 4th, just like you. Fifth gear is a bit much, though. I'll drop down to 5th at 40-45. When I need to accelerate, I'll always downshift first, and I make it a point to do at least some brisk accelerations with each drive after the engine warms up. I've driven like this for almost 20 years with my '92 Saturn (bought new) and more recently with my Z, and I've not experienced any carbon deposit problem in my engines. If it did, I would have stopped the practice long ago. FAIW, I've driven Zs for a total of 20 years (2 different cars and two different stages in my life), and I've always used the standard NGK plugs. They've always worked great for me. I also have about 15 years experience with the inductive core (non-resistive) NGK wires, which I can't say enough about. Your rotor and cap could probably use a refresh, but those aren't as critical parts. And I doubt any cap misalignment would have resulted in the plug reads you've gotten.

FAIW, I like to meet in banks to do transactions. If a bank is handing out the cash, I can assume it's good. I like to do this whether I'm buying or selling. (I think it's reassuring to the seller when I'm buying -- a show of good faith.) Cashiers' checks are a bit trickier. It's reassuring to be there when the bank issues the check, but it is actually possible to stop payment on a cashier's check. (I don't know under what circumstances this can be done, but it can indeed be done.) For this reason I won't take cashiers' checks. However, when I bought my last car, the seller did ask for a cashier's check, which I had issued in his presence at my bank.

OK, Jenny... So despite my best efforts to talk you out of it, you've decided to ditch your old AFM... Grrrrr... We'll keep our fingers crossed that this solves your remaining issues. :bulb: So since you've gone and ordered the thing, it would really be great to glean some calibration points off of it. If you could take some basic measurements on the thing (with the cover left intact over the potentiometer assembly, thus not voiding your warranty), I think I could develop those measurements into a complete and more refined diagnostic and calibration procedure, using my '82 AFM as a reference. I'm thinking you could power the thing off of a 9V battery with alligator clips (a very safe method -- the way I suggested before) and take voltage measurements at reproduceable flap openings. You could also measure the spring tension per Atlantic Z's beer can method. (Even better, you could use a centigram or milligram scale if you have one.) Could I talk you into doing this? Please, please? :classic: With regard to the CTS, it is out of spec, isn't it? It's on the high side, which could be running your engine a bit richer than you would want. These CTSs are hugely important for establishing the right mix -- second only to the AFM. Anyway, yes, you can lower the resistance of the assembly with a simple fixed resistor in parallel, rather than a second CTS. A fixed resistor would be fine for a little tweak, but you could lose temp compensation sensitivity if you have to make bigger changes. In that case (bigger changes), a second CTS in parallel would retain the sensitivity. (Or so goes my theory.) But let's hope the new AFM solves your issues.