As I have mentioned in other threads, when I originally put my 240Z back together I installed a GM style "Single Wire" hot-rod alternator in place of the 40A externally regulated unit. Well, that silly thing died recently, and since I really need the car operational next weekend, I decided to do the ZX upgrade described here: http://datsunzgarage.com/engine/

I went to the local Advance Auto, and ordered an alternator for a 280ZX Turbo, because they are supposed to be 70A units. I am not sure that is really what I ended up with, but the test report that was taped to the rebuilt alternator shows a maximum output under full load of 72A at 13.5V, so I was happy to see that.

I followed the Z Garage directions more or less, but at first I thought he was full of it. The connector to my voltage regulator didn't have all of the wires that he described. THEN I remembered that one reason I went with a single wire alternator in the first place was that some of the wires from that connector broke off when I unplugged it.:stupid:

So, after tracking down the missing wires, and determining their purpose, I was ready to follow the instructions, well almost.

I determined that the white and yellow wires he says to jumper are for the remote sense circuit, which being a very good thing I jumpered as instructed. (After finding said white wire lurking around the wiring harness...)

But, since I really hate soldering while standing on my head inside an engine compartment, I installed the diode in the jumper from the black w/white stripe wire to the white w/black strip wire. The black/white wire is from the ignition switch, so the diode needs to be installed with the "stripe" on the side connected to the white/black wire. This is much cleaner and simpler than hacking up your wiring harness.

Upon starting the car, the first pleasant surprise was that the alternator immediately put out 14V, even at idle! (on my meter that I added to the dash) The single wire unit would never start charging until I bliped the throttle to get its excitation voltage started. Even at that, it didn't like to produce 14V until the engine hit about 1K RPM.

However, my fears turned out to be justified in that with all the electrical accessories running, i.e. Headlights on high-beam, fog lights, driving lights, electric radiator fans, passenger compartment blower, wipers, etc. the voltage falls to less than 12V regardless of engine speed.

I guess it is usable for now, so long as I don't need to drive very much with the defrosters running at night in the rain.

I went to the bone yard , found a 84 Maxima pulled the alt, used Dave Irwin's plug and play in the harness . At idle she never goes negative even with 90/100 head lights and every thing else on. It's a 90 amp. alt and the pulleys do not need to be changed , just a bolt on and go. $32.00

Maybe it is just where I live, but I have had only bad experiences with parts from junk yards. Either they are broken to start with, or they don't last more than a year. To make matters worse, often the prices are higher than the what discount stores charge for rebuilt parts.

There are also a lot fewer junk yards around central Indiana than there were 20 years ago. I guess the increasing land values drove them out, or everyone else had the same bad experiences that I did.

Just a curiousity based question. When those of you that have 240Zs upgrade to an internally regualated alternator, do you have any problems with the ammeter? In my old 320 pickup, after an alternator upgrade, I fried the stock ammeter and later an aftermarket one. After installing a voltmeter, I never had any further problems.

I have been fighting this battle for about a month. The ammeter reads in the negative and the battery does not charge, when i put a voltmeter on the battery it shows that I have 14.2 volts. I had the alternator rebuilt, and the ammeter still shows "-". I am thinking now that I have fried the ammeter. Stephen what was your symptoms when you fried yours? If anyone has a voltmeter fuel gauge from a 78 280 Id be interested to getting it.

Dave

The factory gauge just stopped working. It was the original and designed for a generator so I really didn't have high hopes for it anyway. The aftermarket amp gauge started smoking!

No problems at all, my ammeter works perfectly. What type of device generates and regulates the current should have no effect on an ammeter, all it does is measure the current flow.

I thought as much. My original gauge (in the 320) was old and the aftermarket replacement was cheap.

Is the 78 voltmeter/fuel gauge just a drop-in conversion from the stock 71 style ammeter/fuel gauge, or are there more considerations? I really want to upgrade my stock alternator. Thanks.

The previous owner of my car did this upgrade, and the ampmeter sort-of "vibrates" around the center mark. Is this a problem? If so, what's the fix?

The previous owner of my car did this upgrade, and the ampmeter sort-of "vibrates" around the center mark. Is this a problem? If so, what's the fix?

Sounds like a regulator issue to me. My ammeter is rock steady with the 60 amp ZX system. Far more steady than with the original alternator and points-type regulator. Was the original regulator properly by-passed?

Original regulator was removed. It's an alternator interal regulator.

Since the car is apart, I can't provide much detail. Will have to troubleshoot it late in the year.