Zed Head

His problem seems to be oil-fouling of the #4 spark plug. And maybe #6. His pressure numbers don't show that #4 is different from any of the others. #3 and #4 are 19% higher than #1, which is at 73 psi. But #1 spark plug and cylinder work okay, apparently. #1 plug actually looks very clean in his picture above. Not sure that anything will become obvious anytime soon. Cylinder #4 has the highest pressure of all, along with #3.

jalex should put the engine specifications in his signature. Carbs, ignition system, etc. Can't remember the details. A multi-spark ignition system might help for something like this. MSD. Cheaper than an engine rebuild. The low cylinder pressures could also be caused by an adapter on the gauge. But those are very low, as stated. I think that I used an adapter once and got 125 instead of 175. 80 psi is waaaaay low. I thought the numbers were higher, in past posts. If those numbers were found with a good gauge on anybody's factory stock engine you'd say that the engine was worn out and needed a rebuild.

Have you examined the voltage regulator? Just to be sure that nobody has messed with the wiring. It should be under/inside that shelf that the fusible links blocks are attached to, protected. A small metal box.

Did you verify proper mechanical and vacuum advance operation? Ha ha. Just messing with you. But you were right there... Ignition system complete. On to the next...

Did you guys reset ignition timing after installing the new distributor?

Sounds more like the pickup coil / reluctor system in the distributor. The TIU doesn't know which cylinder is which. But the distributor does.

Could be just bad oil rings. Might be possible to just hone the bores and change rings to stop the fouling. It is an old California Datsun engine. Who knows what he put in there.

Thanks Patcon. My mistake. I saw the word "order" and my brain went to firing order.. #6 doesn't look very good either.

In the correct firing order 4 is next to 1 and 2. There is nothing to argue about. It's either wrong or right. The engine will still run with the wrong firing order. It will just run very poorly. Oops.

Are you sure? It should be 1-5-3-6-2-4. Counterclockwise. Error. Here's an old CZCC thread with pictures.

It's just a bad engine. Bad rings or cylinders or valve seals/guides. You've got many miles out of it. Consider finding a replacement. Or run hotter plugs in the bad cylinders and hope the plugs stay cleaner.

That list is nice but it doesn't tell much about what the component does. Also leaves some things out like the fact that the (L)amp pin is also the field pin. It's dual function. I think that the "tachometer" label is also kind of confusing. My vague memory is that it is meant for sensing proper operation of the alternator components. Pulse counting. Not 100% sure on that. Looks like it can be used for diesel applications also. http://www.vermontficks.org/pic/dtachd.htm Like those old databases that show CV axles for 240Z's once somebody creates the database and everyone starts using it the mistakes last for decades.

I think that they all come from the same place. That number is probably attached to that alternator across sellers. Napa has something different. https://www.napaonline.com/en/p/RAY2138114?impressionRank=1 The problem with reman alternators is that you often have to return 2 or 3 before you get a good one. So Rockauto could cost you a lot of time and shipping costs. Better to buy local. I had a salvage yard 280ZX unit on mine and a new reman on the shelf.

In short - the guys at Autozone sold you the wrong alternator. Either it was in the wrong box or they chose the wrong box. https://www.autozone.com/batteries-starting-and-charging/alternator/p/duralast-alternator-14118/334268_0_0

It might be bad. Don't forget that fan only matters at low vehicle speeds.

Don't know if you were duped but that's not a 14118. It's an internally regulated unit, the P terminal is a clue besides the T connection for L and S. Here's a Rockauto picture of the 14118. https://www.rockauto.com/en/moreinfo.php?pk=37404&jsn=270

The clutch gets stiffer as it heats up. The fan doesn't need to push much air on a cold engine.

It won't move far but you should be able to see it move. I posted a picture years ago showing one that I took apart. The diaphragm inside had grown brittle and cracked. I would guess that on the way to cracking it had stopped moving correctly.

I think that you are correct. A PO from the past might have had more than one Z. They went to the internal regulator in 1978 as you thought. That looks like one of the solid state aftermarket units.

Maybe the full wiring diagram would help. EuroDat put a few colored versions together. https://www.classiczcars.com/files/category/1-wiring-diagrams/

Most likely is a short to ground from a pinched wire. It would be between the load and the power source. Even if you determine exactly what device is powered you'll still have to examine the wires you touched for breaks in the insulation. Might be most effective to take things back apart and look for a damaged wire.

You had a 50-50 chance! It's the other way. Check out pictures on BAT to be sure. CanTechZ just posted but I'm sending anyway! https://bringatrailer.com/listing/1973-datsun-240z-226/

I have noticed that Nissan often offers potentially conflicting specifications. What if you only get one? How do you adjust to get the other? If you look at what the point of all of the parts is the most logical spec., I think, is the end play. That determines where the balls are riding in the race. And that's the most important thing, I think. If I was doing one I'd just get up to the minimum torque on the nut and stop when I got the end play right. Maybe even go up to the high limit, back off, then retorque to proper end play. Kind of like setting a front wheel bearing.

This is interesting and something I've wondered about in the past. Many of the how-to's you'll find out there use the nut to pull in the bearings. But the instructions say that one of them should be pressed/pounded in using a special tool. Seems like #6 should come before the nut tightening.

I think that the range of the torque value is meant to allow you to find the 3.9 inch-lb point once you get past the minimum. Have you measured the B spacer? It is meant to match the B dimension in the strut casting. Apparently the spacers, or distance pieces, can get mushroomed after overtorquing or impacts during use. L1 is spec'ed to match L2. The range overlaps, by a little. Don't know why they call it L1 and L2 in the drawing, then housing and distance piece in the table. But you can figure it out. There's an obvious typo too. Forgot to say also, that sometimes the seal can cause noticeable friction, apparently. Haven't done a set myself.