FastWoman

So here's my setup for spring tension: 1 sheet of 20 lb copy paper, folded up into a cup, with 3 staples securing it. 1 short length of string taped to the flap AFM with air outlet facing down, sitting on level table 22 pennies will just open the flap (on my seemingly unmolested '82 N/A ZX AFM 28 pennies will open the flap approx parallel to the table 238 pennies will open the flap fully I'd try quarters, but I don't have many. Notes: My pennies are 2.56 g each, and my paper/3-staple/string rig is 4.93 g (approx. a 2 penny equivalent). I'll try voltages next.

Zed, I really like your idea of volts against quarters! Here's my thought: Use pennies instead. They're ligher, and people generally have more of them sitting around. But otherwise, yes, great idea! It makes sense to me that the AFM is designed to be just leaky enough to pass idle air without (much) movement of the vane. It makes no sense to have the AFM sensitive to sub-idle air flow. That would explain (to me) why the vane would be designed to be under tension even when fully closed. I think the spring constant CAN change. The metallic properties of the spring might change over the years, and I suppose the thing could even rust. What would change the spring constant would be the length of free spring between the two attachment points. In fact this is how mechanical clocks/watches are regulated. So I suppose the first thing is to get the just-opening and full-open tensions right. Then the voltage/pennies curve could be measured from there. I'm going to go grab my '82 AFM and have a look...

Zed, thanks! My thought is that the following could be used to calibrate and verify an AFM: Spring tension: Force needed to open the flap just far enough to close the fuel pump cutoff switch (or to just open the flap if there's no fuel pump shutoff switch. Voltages: Full closed, full open, and perhaps some reproducible increments inbetween. Perhaps this could be done by measuring distances the flap is deflected. There are certainly some landmarks on the potentiometer board that could be used if one is to open up the AFM cover. However, I'm wondering whether it could be done accurately without even opening the cover -- maybe by marking increments on a monofilament line with a sharpie. Or maybe the increments could correspond to the landmarks on the potentiometer board. Your idea of using coins is good, except for our friends in other countries! Even aluminum cans differ between countries. Anyway it would be great to make this work. There are so many people questioning their AFMs, and it would be great to have a better method for making certain everything is up to snuff.

It could be any number of things. You might try cleaning the potentiometer assembly beneath the cover of the air flow meter (AFM or "air-box"). If it's dirty, you might get false readings. You might also try cleaning up electrical connections. Most of them are probably getting pretty crusty. FAIW, several of us have been dealing with lean-running conditions in our EFI 280s and have found that the ECU has drifted. Cozye and I have both corrected this problem by inserting extra resistance in the coolant temp sensor circuit to force the ECU to run the engine richer. However, before we could do this, we had to get EVERYTHING ELSE right with our engines (to know that we weren't simply compensating for a fixable problem -- e.g. a vacuum leak).

Argneist, I already responded to your other thread. Check there.

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.