FastWoman

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.

Walter, the '75 and '76 hoods actually didn't have the vents.

Those are some pretty odd looking plugs. Ideally (and ordinarily) they would all look approximately the same -- preferably somewhere between your #1 and #2, but a bit closer to #2.. If your carbs were out of balance, you'd have two different plug appearances in the two banks. So I'm thinking maybe you've got some ignition problems on just some cylinders, but not all? Are your wires good? Are your spark plug gaps all the same? Do you consistently hit on all 6 cylinders, or does your engine miss a bit? I'm also wondering whether you have any compression issues. Your two nastiest plugs are adjacent -- the #3 and #4. Head gasket problems? The whitish coloration of #2 and #6 is from lean running. The carbon buildup on the other plugs is from incomplete combustion and/or oil combustion. Causes could be... *rich mixture *extreme lean mixture *cylinder misfiring (bad ignition) *low compression *oil leakage into cylinder (valve guides, rings, head gasket) Maybe it's a weak link sort of thing. For instance, maybe your ignition coil is failing, and your #2 and #6 plugs consistently spark, having a very slightly closer gap than the other plugs, which aren't consistently sparking. Could be many things. Dunno.

Kinda like the G-nose w/o the headlight covers.

I wonder if just a spot of RTV under the clamp would keep everthing in place.

Jenny, if your CTS is out of spec, I'd replace it anyway. It's not a very expensive item. Unfortunately it's a bit hard to get a wrench around, but mine wasn't very hard to remove (not corroded in place). I did end up removing the thermo housing from the side of the head to give me access for removing an exhaust manifold stud, so it was much easier for me to access the CTS. In hindsight, it's probably a good idea to remove the thermo housing every now and then anyway, to keep the bolt threads clean and workable. The gasket is quite cheap. If you do need to alter the CTS circuit resistance, remember that you can either increase the total resistance by adding resistance in series (richening the mix) or decrease the total resistance by adding resistance in parallel (leaning the mix). In fact if you needed to cut the resistance in half, you could probably use that un-used threaded hole in the thermo housing for a second CTS, to be wired in parallel. There are options available. We just haven't figured out what you need to do yet. Zed, that's a cool idea about using a shop vac. I wonder whether there would be some way to standardize that. It would be great if we could develop more accurate calibration methods for our AFMs. It might be a worthwhile project for us, collectively. FAIW, the Atlantic Z beer can article talked about two different years of AFMs that supposedly had the same spring tension (testing unmolested units). I think one of them was even from a ZX.

Awolfe, what everyone else said. I, too, was surprised the V meter always stays on. IMO the current draw isn't infinite or near-infinite, but it is very small in relation to the huge battery. It shouldn't pose any significant battery drainage problem, any more than your clock or the memory on your stereo. In fact the battery would probably lose voltage faster on its own than through drainage by these tiny circuits. You can get fusible link wire from your local auto parts store. Off hand, I don't know the proper gauges or ampacities, but that info is buried throughout this thread: http://www.classiczcars.com/forums/showthread.php?t=35588

Sounds like a plan. That would at least give me a bit more upper body strength than I really have. But first warm weather... ... and then trying a change of fluids...

Cool! Thinking outside the box, would it be possible to put a loop of rope around the transmission, pass the ends through the hole for the shifter (i.e. in the body), and have someone lift on the transmission from inside the car while I do the positioning from below?

It's true that the gasoline would expand. But then there's a question of the elasticity of the system. The fuel pressure damper in the fuel pump assembly (which comes after the fuel check valve) should absorb small changes in volume without substantial changes in pressure. I'm pretty certain the pressue rise would be due to fuel vaporization (from heat soaking). It would be interesting to pull off the return fuel line after engine shut-down to see how much fuel is ejected.

^^^ What Cozye said! BTW, don't use muriatic acid to eat out corrosion in the tank unless you intend to POR15 coat it afterwards. The tank is galvanized, and the muriatic acid will eat away the zinc.

Well, I've never done a car transmission, but I did an R&R on our boat transmission, which probably weighs about 50 lb. I just lifted it into place. Of course working over my head would be more difficult, but if I can simply get the transmission supported somehow, I feel I should be able to align it. How long is the spline? Is it possible to get that started before seating alignment pins?

Buddy, that happened to my '75 long ago. It's pretty baffling to run out of gas when the tank is half full! You don't need a new tank, though. Just take your tank to a good radiator shop. They'll be able to repair it fairly economically.

Jenny, it's easy to surface-solder. See if you can find some junk piece of electronic equipment around that is destined for the trash. Pull out a PC board and practice on that. You'll find it's pretty easy. You can get a soldering iron (probably 30 or 40 watt) and some rosin core solder at Radio Shack. General soldering instructions can be found on youtube. If you want, I can measure R0, R of the potentiometer, and R10 off of my spare AFM, which is off of an '82 ZX. I'd hate to open up the AFM on my car, though, as it'd make a huge mess. Besides that, the AFM *might* have very minor issues. Before you get into that song and dance, though, you might want to check your voltages with the AFM full-closed and full-open, so that you can compare them to Zed's. You don't need to power the AFM off of your car battery, if that makes you nervous. (I admit it'd make me a bit nervous too. I bench tested my AFM with a regulated power supply that was current-limited to 1A.) You might pick up a battery clip of some sort at Radio Shack. It doesn't matter what type. The cheapest would probably be a 9V battery clip. Solder a couple of alligator clips onto the wires. When powering the thing off of a little 9V battery, you won't have to worry about blowing anything up. Then just consider all your voltages in proportion to the supply voltage (roughly 9V, which you should measure while the battery is under load). All of your voltages should be proportional to Zed's. Finally, even if your AFM is slightly askew, you can probably still use it. All you need is the proper mechanical properties (spring tension) and a smoothly working potentiometer that won't send "jumpy" readings to the ECU. You can compensate for any errors in the AFM by altering the coolant temp circuit's resistance. I don't know if it's in your '76 FSM, but my '78 FSM states that this resistance determines the multiplier used on the duration of the injector pulse across all operating conditions (or words to that effect). Your mix might not be perfect across all conditions with this tweak, but it will be pretty close -- certainly as close as anything else on this primitive EFI system.

Well, when some people shut off their engines, their fuel pressure rises for a while before it falls. That could only be caused by fuel vaporization. Depending on how much heat is transferred to the fuel, the vaporizing fuel could push liquid fuel through the fuel pressure regulator and out the return line. Then when the fuel cools, there will be a vacuum. The vacuum might draw additional fuel through the fuel pump and into the fuel rail, or it might draw air through very slightly leaky injectors (or both). Wrapping is an easy way to lessen this problem (if it is a problem), but I wouldn't go to too much effort or expense to do it. It was easy for me to do when I replaced my injectors, so I did it. FAIW, I had some extra room under the hood of an old Suburban when I was younger and more foolish. I filled that space with a 1 gal gas can with emergency gas. (I was doing a lot of work in desolate areas at weird hours of the morning.) It wasn't long before the gas can had almost completely been destroyed. Engine heat would boil the gas, and then the vacuum would collapse it. Repeat, repeat, repeat. Boiling gas can create quite a head of pressure!

More like an arthritic old lady! I don't get along at all with the cold!

Tell him he'll need to pay off the balance in cash. A cashier's check can be no good. (I'm not talking about forgeries, which can happen too.) Call your bank to ask them how long you must wait to be dead certain the funds are good for the first half of the payment.

Ztrain, that won't hurt my transmission, will it?! Anyway, warmer weather!

Oh, I didn't see the prior posts! Willoughby, thanks! I might take you up on it. OTOH, I have a neighbor just down the street who restores a LOT of motorcycles. I bet he has one too. Steve, that sounds like a pretty useful approach. I might be able to cobble something together from wood for just the one job. I'm thinking of something on the end of a plank. One end of the plank sits on the ground, the transmission is strapped to the other end, with shims to tilt the trannie as needed, and the transmission end is jacked in the air by an arm extending off the end. But again, I'm waiting for warmer weather and will be trying Redline and a clutch bleed/flush first.

I don't think I've tried. Why?

Well, despite any particular person's BS content, I think there's something to learn from almost everyone. To wit: I had never considered a garbage bag test. Interesting. I remember participating in an exercise physiology experiment once. (I was in the control group! ) Our exhaled air was collected in a garbage bag. Its volume and and gas composition were measured. Now on a car, exhaust rate would be a measure of running efficiency. The more exhaust the car blows in order to maintain the engine at a given RPM, the less efficient the engine is. For instance, if you severely lean out an engine, and then adjust the throttle open enough to restore the RPM to the prior level, you'll be blowing quite a lot of air through the system. The exhaust will blow rather hard. The same would be true with the engine running with the proper mix, but under load, with the throttle cracked to compensate for the RPM sag. I suspect the OP's "worked" engine is running either leanly or inefficiently, compared to the stock motor. (Sorry!) However, this is still an interesting test for operating efficiency, particularly with regard to adjusting fuel/air ratio. These would be the properties, with the engine at a fixed RPM and not under load: extreme lean: Hard-blowing, randomly puffing exhaust, spitting condensation. Quick bag-fill times. Low engine vacuum. Incomplete combustion, with unburnt hydrocarbons (soot, gassy smell) in the exhaust. Sooty plugs. somewhat lean: Hard-blowing exhaust, spitting condensation. Quick bag-fill times. Low engine vacuum. Clean-smelling exhaust. White, chalky looking plugs, with possible electrode erosion. correct: Longest bag-fill time, highest engine vacuum. Clean, mocha plugs. somewhat rich: gassy smelling exhaust. Relatively long bag-fill time. High engine vacuum. Sooty plugs and sludgy engine. extreme rich: Gassy smelling exhaust, with black smoke. Shortened bag-fill time. Low engine vacuum. Extremely sooty plugs and engine sludge. That said, I think the bag-time test would not be as accurate, sensitive, user-friendly, or useful as a vacuum gauge, the two being essentially redundant for determining the correct AFR.