Zed Head

FW is right. Compost is the key word. Hey, regarding the yogurt cup leak down test: I had realized in the past there is one potential difficulty with the test. Overlap. The intake and exhaust valves are both open at the same time for just a few degrees at the end of the exhaust stroke, beginning of the intake stroke. For a stock cam, according to the cam card, it looks like 30 degrees out of 720, or about 4% of the time. A 4% chance that your intake will have a big leak right through a cylinder to the exhaust. So if you get a big leak, run the test again to be sure you're not sitting on the overlap.

Ben's Z might be on to something. I had an external water leak between the head and the block that would seal up when the engine got warm. The cooling system held pressure fine when hot, it just leaked a small amount of hot water while the engine was heating up and cooling down.

Edit - I wrote a most excellent reply here but decided not to fuel the compost pile and erased it. Your fuel pressure should be 36 psi. Your engine is running lean, assuming that your gauge is correct. You either have a supply blockage or a bad fuel pump. Get the fuel pressure up to 36 psi (test it with the vacuum hose to the regulator removed). The turbo engine will be more difficult to handle than what you have currently

The slot in the assembly is designed for the "plate-lock" (Nissan term, #63 here - http://www.carpartsmanual.com/datsunS30/DatsunZIndex/PowerTrain/TransmissionGears/5Speed/tabid/1708/Default.aspx.) It determines the orientation and the depth of the assembly. The later 5 speeds have a different assembly than the early 4 and 5 speeds. I have the 17 tooth gear in my transmission,with 3.54 rear gears and 205-70/14 tires (25.3" dia. by internet calculator), and my speedometer works perfectly. The same calculator shows your tire as 25.1", so the 17 tooth is probably as close as you'll get, IF you have 3.54 gears. http://www.1010tires.com/TireSizeCalculator.asp?action=submit Swapping gears looks pretty easy, a small roll pin just needs removing and replacing. Any stock 280Z with an R200 should have a 17 tooth gear, I think that they all came with 3.54 gears. I have 76 4 speed, 78 5 speed and 83 5 speed in the garage. I might be able to get a picture if you know what you're looking for. Here's a couple of links, that you may or may not have seen that might give you some ideas - http://www.geocities.com/inlinestroker/ratio.html Look down at the bottom of this page. http://home.comcast.net/~zheimsothtn/transmission3.htm Note - the picture in this link doesn't tell the whole story since there is actually an upper and lower lock plate orientation for early and late B type 5 speeds. It has good pictures though.

Does the Charge light turn on when you turn the key to On, before you start the engine? Sounds like the Lamp terminal is not connected to the Lamp wire from the harness. That wire provides the initial current to magnetize the alternator so it will start charging immediately. Find the wire from the Charge Lamp and connect it to the L terminal n the ZX alternator.

I got the ratios from the FSMs. Of course, they could be wrong. I thought it was odd also, but it's in there. The 3.36 R200 is an oddball also. I didn't realize that the turbo diffs had a different pinion flange. By similar reasoning as yours, why wouldn't they have the same pinion flange as the 280Z 3.54 long nose R200s? Seems odd. I tried to deduce pinion flange type by the pinion flange special tool described in the FSMs. The tool changed in 1984, and the turbo supplements I have don't show a different tool. Oh well, new knowledge. A few loose ends to tie up for garretthes, but overall not a tough job. Except for the pinion nut. Do you have recommendations on how to hold the pinion flange while removing or tightening the nut, if you don't have the Nissan special tool?

The ZXes had both available. They're shown in the FSMs, Prop and Diff section, all the way up to 1983. Anyway, I've been in the same boat with two 3.54 gear R200s. Swapped one for the other and they both sounded the same, even though one had fewer miles. One trick people do is to run 85-140W gear oil in place of the 75-90W or 90W spec. Lowers the volume of the whine.

The R180 is smaller and narrower and has a more square back cover, the R200 is more rounded and bigger. It's easy to tell if they're side by side, but difficult to describe. Compare the 83 to the 79 and it should be apparent, the 83 Turbo diff should definitely be an R200. There are pictures around the internet. Post a picture of yours and someone will be glad to identify it. I realized also that your 79 could have 3.36 rear gears. Still not the 3.54s that the turbo diff would have. If they are both R200, it's really not as complicated as it sounds. The stub axles and the CV shafts both use internal clips to hold them in, so they are designed to pop out with a dead blow hammer or a wedge against the housing. The speedo gear can be a little more difficult because you'll probably need to remove the roll pin to get the gear off. Still not a huge undertaking. Is the turbo an automatic? I'm not sure about the speedo gears from those, you might need to do some research on it, or find the right gear from a different manual trans car. Worn mounts can allow more vibration to enter the cabin. I don't know a bunch about ZX diff mounts though, they are different form the 280Z mounts.

I've seen P90A heads on non-turbo cars in the local wrecking yards. I don't know how they got there, or what pistons were in the F54 block, but the P79 and P90 heads have the same combustion chamber volume, so if you have flat top pistons, you would be around 8.8 CR, like the stock NA F54/P79 setup. As LeonV suggests, check through the spark plug hole with a strong light to see what you have.

It looks like it's almost already closed. That should be fixed. That type of pump does not like to have a restriction on the inlet side. The way to get the pump where you want it, with no kinks in the lines is to run a loop, or big circle, of fuel line on each side. The loop will avoid kinks and let you build a nice, rubber insulated mount for the pump. You don't want to drive the car with the pump flopping around on the fuel lines, and you don't want to strap the pump body directly to the metal mount. It will be very noisy.

So back in Post #4, maybe the removal of the plug wiggled it to the "bad" no output state? Just trying to get the full picture, it sounds like your second test gave different results. I've come to the conclusion that old used Nissan alternators are better and will last longer than "new" auto store rebuilt alternators. Just an opinion. My old used Nissan factory alternator puts out more voltage at idle than the rebuilt auto store alternator I had on there for a while, that died after nine months (~10,000 miles). The literature in the rebuilt alt's box said something along the lines of "all parts are tested and those that fail are replaced." In other words, the old parts are re-used if they pass the function test. In even more other words, parts that could be on the verge of failure are re-used. I think that's why so many rebuilt alternators fail quickly.

It should be a direct swap, if both are R200s. You'll need to remove the stub shafts from the 79 diff and install them in the 83 diff, which should have CVs that are plugged directly in to the diff. The gear ratios will be different also, 3.54 for the 83 turbo diff and 3.7 for your 79, if they're both stock. So you'll need to swap the speedo gear in the transmission to get the speedometer to show the right numbers. After all of the work, the odds are pretty good (bad?) that the 83 diff will whine also. They all seem to have some whine to them, I've even seen it noted in some old Car & Driver new car tests. You might have better luck trying to isolate the noise.

Put the nut back on and screw it down part way, leaving the threads on the bolt covered. Tap on the nut with a hammer to break it loose. Or use a plastic hammer to be even safer. It's the same type of tapered lock bolt that used to be used on old bicycle cranks. After you get it out, squirt some Liquid Wrench or PB Blaster in the hole to help loosen the spindle pin. Don't go much farther until you read the "spindle pin" search results.

The plates in the distributor are for "phasing" the two pick up coils (for electronic ignition, maybe for dual points in a 240Z also), if they're installed. You still need to use a timing light to set timing. Besides the N42 block, you could also have an F54 block, and/or a P79 or P90 head. The casting numbers are in the same spots though. Is the engine set up for carbs or did they transplant the EFI? And the distributor might be electronic or points. That would determine what your plug gap should be. Pictures are always good, for you and the viewers.

Here's a helpful web site - http://www.nadaguides.com/Classic-Cars

Inward. There are pictures and drawings all over the internet, including this forum, if you want to be positive.

I know that the oil pressure sending unit hole is BSPT (British Standard Pipe Thread). I got an adapter from McMaster Carr for BSPT to NPT so that I could use a mechanical gauge. Looks like they might have a plug for the water hose port also. The hose is 5/8", maybe the hole in the block is 3/4". How to measure is at the top of this page, along with some brass plug options - http://www.mcmaster.com/#brass-british-standard-thread-pipe-fittings/=f40iqn

Maybe when you removed the L wire you lost the excitation current through the windings and it quit charging. I've read that some of the cores used in various alternators have enough residual magnetism to work without the L wire's excitation current, but some don't. Guess you'd have to run without each, S and L, separately to know for sure. Two variables. Just though of another possibility for odd behavior. If the L wire shorted to ground, instead of through the regulator circuit, the light would come on. Did the voltmeter stick at 12.6 while the light was on the first time? No idea on the battery. Depends on it's capacity, I believe. Must be fun to have a new problem to work on.

Ignition modules seem to fail in many different ways. I just gave my example for reference. As Blue suggested, if the tachometer needle drops dead while the engine is still turning, that's a sign of electrical failure. If it was fuel related the tachometer would still show RPM, since it gets its signal from the coil, even though the engine wasn't producing power. So next time it dies, watch the tach needle, either right away while it's still in gear and you're rolling, or while you're trying to restart it. I think that the only port in to the fuel tank, besides the filler hose, is on the side of the tank, not the top, although there might be an access panel from inside the car. There's a picture in the FE section of the FSM, but no description of an access panel.

Have you checked your lug nuts? That's the only thing that you would loosen and tighten for a brake job.

Seems like you would lose voltage regulation without the S wire connected, and get maximum output. You could connect a rheostat to the S wire and vary the voltage it allows through while watching a voltmeter. That would avoid damaging spikes and just look like lots of load to the regulator circuits. When my OReilly auto parts rebuilt alternator was going bad, the charge lamp started to glow very dimly, even though the voltmeter showed normal voltage output. Eventually, the charge light brightness increased with RPM, like some sort of "RPM by brightness meter", while the voltmeter needle sat steady at ~14 volts, which made no sense at all, by typical "how things work" knowledge. While I was being fascinated by the weird behavior I think it destroyed my ignition module.

There's a drain plug on the bottom of the tank. Disconnect the fuel line to the filter and run some extra hose to a spare gas can or two. Use the fuel pump to push the fuel out through the fuel lines (disconnect the starter line and use the key at Start or hot-wire the pump), then drain the remaining gallon or two through the plug and see what comes out. The pump will either stop pumping due to debris buildup while it's running, or you'll find some crud when you drain through the plug hole. You'll need to do this any way before you remove the tank. If the pump runs fine while draining the tank and no crud comes out, you can always change your mind. As far as the ignition module goes, when mine was failing (1976 car like yours), I could bring on the failure signs by running over ~3,000 RPM. It was okay below there, but as soon as I went above that number, the tach needle would start bumping around at a higher number than the engine was at, and the engine would start missing, stumbling and wouldn't idle. My alternator was in the middle of its failing process and I think that the stray voltage spikes hurt the module. As Blue suggested, the tachometer will give some signs of ignition module failure.

If you post more results from your tests, you'll get more feedback. So far you've only shown cylinder pressure numbers (which looked pretty good to me). Have you been driving the car, or has it been sitting in the garage since 3 days ago when you noticed the white smoke and the gassy oil smell??

Oops. Didn't re-check the details of your setup. At least the E12-80 ignition module is close, on the distributor.

Just realized that you could also disconnect the negative post of the coil. If the lights stay on, the short is on the positive side (and negates my proposal), if they go off, it's on the negative side. Gets you closer.