SteveJ

The 6-pin connector doesn't look properly seated. You may want to take it apart and put it back together again. That could fix your running lights. For the headlights, there should be a black wire going from the turn signal switch over to the ground on the right side of the steering column. I didn't see that one. For the turn signals/brake lights, go here: https://fiddlingwithzcars.wordpress.com/2013/01/20/hazard-switch-brake-light-turn-signal-circuit-analysis/

I actually found a thermostat housing like the one @kully 560has - https://maseraticompound.com/products/datsun-240z-thermostat-housing

Yeah, that's not stock for a 73. As I mentioned before, the roadster belts could be installed in such a way that you won't have the belt retractor in the way.

This link may be cheaper. https://www.ebay.com/itm/154916677637?chn=ps&mkevt=1&mkcid=28

I improved my search by specifying AGC fuse holder. https://www.delcity.net/store/AGC-Adjustable-Fuse-Holder/p_800425.h_800426 Del City is reputable, and I have purchased from them.

A possible source for holders that aren't pre-wired. I have not done business with them. https://www.asi-ez.com/member/~PTF-80.asp?shop=y

Also, when I changed out the old seatbelts in my 260Z, I bought the roadster style seatbelts from Wesco Performance Products. https://www.wescoperformance.com/nsearch.html?query=roadster I put the retractor at the top mount.

That is not a stock retractor. The stock retractors fit in a pocket in the floor. Post a photo of the top mount.

Inline glass fuse holder. I can only find pre-wired ones now. I bought some on Amazon 4 years ago that were not pre-wired, but they are no longer available. 250V is the voltage rating. Since you have a 12 volt system, there isn't a problem.

It's Mitty weekend at Road Atlanta. I spent a few minutes with Greg Ira and Scott Hyatt in the paddock after their first qualifying session. Greg was top dog in that session. He may have shown his hand too soon.

Emissions testing would be real there.

If you want to come down this way, I think the Georgia Z Club is planning on going to the PoBoys Cruise In in Canton. I think that's a little over an hour and a half from you. The Cruise In is the 3rd Saturday of the month, and I think we're planning to show up in June.

The output is on the low side. What was the RPM for that voltage? What is the voltage at 2000 RPM?

I know what you were talking about. That's why I told you where you could source the correct size fasteners. https://belmetric.com/coarse-thread-jis-small-wrench-hex-nut-class-8-steel/? https://belmetric.com/coarse-thread-jis-small-wrench-hex-nut-class-8-steel/?sku=NJ8X12YLW (Yellow Zinc) I bought 100 of these.

By the way, if you want the 12 mm head M8 nuts and bolts(JIS spec), you can get them from Bel-Metric.

A friend of mine with over 30 years experience wrenching on Z cars doubles up on the gasket when installing headers. For instance on my L28, I had two Beck-Arnley gaskets with a generous amount of Ultra Copper to adhere the gaskets to one another.

I have been driving the 240Z so much lately that I wanted to take the 260Z out. You can't have them feeling neglected, right? There was a car meet half an hour away. I had the only Z, but it wasn't the only Nissan. There were a couple of JDM Skylines, a Roadster, and a GTR. (Does a G35 count? 😉 )

I'm just glad that you weren't somewhere underneath when it happened.

Good job tracking it down. I can only point you in the right direction. You have to put the effort into it to find the root cause.

Is the horn relay still connected? If the wiring is stock, the only way for there to be a complete circuit is for the green/black wire in the steering column to be connected to ground. When you press the horn button, the button connects the tab on the horn wire to the steering column. You may want to take the cover off the steering column and make sure the combo switch wasn't installed too close to the steering wheel. Is it a stock or aftermarket steering wheel?

That would tell me there's a problem with the alternator.

No. If there isn't a load, such as a light on, a hot fuse won't cause a drain. An internal voltage regulator is still a voltage regulator. A failure of that component could cause a battery drain. For some reason I missed your question. ONLY the circuits in red require the key to be in the ON position to be energized. You can turn on the headlights and parking lights with the key any position. So, going back to my original questions, do you know how to use an ammeter? If not, do you have a test light? One or the other is likely to be necessary to find a cause for draining the battery. Have you checked all of the other items I listed for potential drains? Again, how long does it take the battery to drain?

That's okay. There is the switch between the fuse and the lights. As for battery drains, check the list I supplied.

It sounds like the voltage regulator. I ditched the externally regulated alternator on the 240Z so long ago, I don't remember if there was a clicking sound when I plugged it in (last replaced in 1995). On the 260Z I only unplugged it once and never plugged it back in. They shouldn't be getting warm, though. The 0.5A draw is pretty strong. I bet it goes away with the regulator unplugged. It looks like you are running a points style VR. Have you opened it up and tried to adjust it per the FSM?