SteveJ

With some studying of the wiring diagram, that could be figured out. For instance let's look at the switch. From the attached image we can determine the following connections at the different switch positions: Off LY - YB In LY - YB YG - WR (12VDC) Low WR - YB WR - YG High WR - LY WR - YB Tracing those wires will probably take us over to the amplifier circuit. From seeing what connects where and the other diagram in the BE section, we can probably figure out the function.

So he was using a relay with 2 form A contacts?

It's not like there were a lot of options for the North American market. Don't take this the wrong way, but you're on a fishing trip. Tell us what you're trying to catch, and we can tell you if it's worth the effort or where to find the fish. In other words, your question is a little on the vague side. Are you trying to find info to have a period correct restoration or what?

No. The VIN does not have that info.

Check the BE section of the FSM.

Phil, would you post a link to the site where you found that if you remember where it came from? Edit: From what I could find, the FL series of fusible links are for modern fusible links.

I'm not the most mechanically inclined. (Translation: I manage to fix more than I break.) I dropped the tank in the 73 enough to replace a bunch of old hoses. It wasn't that painful.

Since it's a 74, the seatbelt interlock could be the culprit. Details given in a PM.

I think I saw them for $263 + $8.50 S&H each on Amazon.

If you haven't already done so, I suggest that you also incorporate relays into the design. Getting 12VDC to the headlights help, even for LEDs.

They are definitely to reduce heat transfer to the carburetors. It's bad enough that they have to sit over the exhaust manifold. Why have them get heated up from the intake manifold, too?

Yeah, that's right. It's 4 gauges. I remember reading that, too. I was thinking 2 when I was typing because you usually don't see the odd number wire gauges. Thanks for catching that, Phil.

We had a good discussion on fusible links just a couple of days ago. Anyway, the gauge of the wire in the circuit gives a good rule of thumb for the ampacity of a fuse to protect it. Though the 0.03 mm fusible link would translate into about a 20 AWG wire & fusible links tend to be 2 gauges smaller than the wires they protect, I get a feeling that the wires in the circuit are probably around a 14 AWG. You don't want to pump more than about 30 Amps through those wires and only for a very short time. If the gauge of the wire in the circuit is actually larger (I don't have a 280Z.), then my guess would be that there is a component that needs the protection. As for why it would be different from factory...sometimes factory engineers get things wrong. Also, sometimes standards are revised due to lessons from experience.

IIRC the best way to get to the heater core is to remove the dash. While it is a pain, it's still easier than on modern cars.

To expound upon Gary's post, fusible links are wires that are two gauges smaller than the wire in the rest of the circuit. They have thicker insulation than the other wire, too. These links will burn up a current well below the ampacity of the wire in the rest of the circuit, and if it functions properly, the insulation will not break.

Green circle - Fusible links. Covers are available through MSA and others. Fusible links available through Courtesy Nissan.

A hot fusible link happens during an overcurrent condition. Check & clean all your fusible links. Replace the bad one. Courtesy Nissan does have the fusible links available.

That's not a good idea. The fusible link is designed to protect the wires in the car. To select the proper ampacity fuse, you would need to consider the current carrying capacity of the wires in the circuit. The rule of thumb for 10 AWG wire is 55 Amps (NEC 90 degrees in free air. Bundling the cable drops the rating some.) An 80 Amp fuse could allow the wire to overheat. Don't forget that while your alternator may only be rated for 60 Amps, your battery can deliver a LOT more when you have a short circuit. (If you want a demonstration of that, lay a metal wrench across the battery posts and see how fast it welds to the posts. )

Suggestion: List your Z in your signature and/or profile. I'm going to assume you have a 240Z since the fusible link gauge isn't listed in the 72 or 73 FSMs to my knowledge. The fusible link for a 240Z can be purchased from MSA or Banzai Motorworks. Yes, I know I didn't answer your question directly. I haven't found what I consider a trustworthy conversion of fusible link gauge to ampacity. I know that Mike at Banzai is a stickler for details, so I would trust that he used the correct gauge wire for his fusible links.

Phil, Try looking here. The picture isn't too good, but you might be able to find it. Of course, I just remembered that I have the parts catalog. This scan should work better:

Look at the parts link for the windshield washer reservoir. It will give you approximate dates for when the part was used.

I'm wondering if it's fuel, too.

It's probably not the alternator, unless the voltage is decaying. Did you check your timing w/o load? Is the advance working? If the advance isn't working, you may be able to work around it by advancing the static timing a couple of degrees. By the way, I wasn't sure whether or not you could wait on the mounting plate. I might be able to get to my distributor swap in three weeks.

In the list of materials to do the modifiecation, include the rubber gaskets for around the headlights, especially if you haven't touched your headlights in a while.

Well, I looked at my 260Z with the wiring diagram. The joy of owning a 260Z is in determining whether you have an early or late 260Z. I have an early 260Z. I think some components were moved around in the engine bay between the early & late cars. The first picture shows my fusible links and interlock relay. They are mounted against the firewall. The second picture is the emergency start override for the interlock relay. It's located near where your fusible links are. The wire for the AC compressor relay is near it. Anyway, I couldn't find a stock yellow wire with a connector like the one in your picture. I'm sorry I couldn't be of more help.