SteveJ

The short answer is that it won't work. The longer answer is that you will never have sufficient current flowing through the second relay coil. You have a parallel path to ground. I've made a simplified drawing of your circuit that I hope allows you to see the issue. If you removed the high/low beam switch from the car and had the headlight switch on, you would find you have 12VDC to ground on both the red/black wire and red/white wire. The headlight would not be shining, and the filament just acts like an ordinary piece of wire. In your drawing, you have the low beam circuit on a normally closed contact. That gives it a straight path to ground. This actually renders your other design flaw moot. The second flaw is that the headlight and second relay coil are in series. The relay coil has a resistance of around 80 ohms. The high beam filament has a resistance of less than 4 ohms. Since they are in series, that means the voltage drop across the coil is going to be at least 20 times more than the voltage drop across the headlight filament. At less than 5% of its designed operating voltage, the headlight would not even have a dim glow. All working examples of headlight relays isolate the positive and negative for the relay coils from the positive and negative for the headlights. Also, it's smarter to have two positive wires and one negative wire for the headlights in case you ever want to use LED headlights.

The downside is that my wife has already reported me to HR...twice.

To elaborate on what @Patconsaid, if you don't have the coil wire firmly seated against the contact in the distributor cap, you WILL have arcing between the wire and cap. This arcing will heat up a destroy the center post on the cap. I actually got a $700 discount on my 260Z because of this. The owner planned on selling it for $3200 but knocked it down to $2500 because it wouldn't run. With a new cap and new plugs, it ran fine. He still sold it to me for $2500.

Pop a huge bowl of popcorn for this one. The audio isn't great, but the subject of the interview is.

He's in Madison, WI.

I'm glad it worked to your satisfaction, Ron. From the first of my research, I read that the LED color should match the lens color. I might have used some white LEDs in the center gauge pod, though. It's been long enough ago that I can't remember. The bottom line is that you will be able to see at night. I suggest that you replace the 20A fuse in the parking light circuit with a 10A fuse. The wiring wasn't really up to handling 20A, so if you get a short, you could melt wiring (or a connector) with the 20A fuse.

If you retard the timing too much, the engine won't run. You can run the car with the static timing at 30 degrees. It will ping like crazy if you aren't running racing gas...So I've heard from a friend.

While the tach is out, you could use a meter like this one to test the signal going to the tach. https://www.amazon.com/gp/product/B0002LZU7K or https://www.amazon.com/Mrcartool-Digital-Multimeter-500-10000-Temperature/dp/B07VKLKDZL Connect the positive lead to the blue wire and connect the negative to ground. Put the meter on 6 cyl and start the car. If the signal isn't consistent, then you have a different issue to track down. If the signal is good, your tach is going bad.

I just happened to remember the thread.

If the Speedhut gauge sensor is 1/8 NPT https://www.amazon.com/GlowShift-Female-Sensor-Adapter-Reducer/dp/B00NWZZBS6 or https://www.amazon.com/Fitting-Female-Metric-M16X1-5-Adapter/dp/B07GRT81L7 If the Speedhut gauge sensor is 1/4 NPT https://www.amazon.com/Fitting-Female-Metric-M16X1-5-Adapter/dp/B07HGVF2PY or https://www.amazon.com/Fitting-Metric-M16X1-5-Female-Adapter/dp/B07DJZKQHY

I believe it's the same as the 240Z.

He had several opportunities to practice his recoveries over the weekend.

Let's go for a ride.

Here's a quick video. My nephew was filming this at the last Mitty. Watch for the Alfa that's a few cars behind John Morton. I was closer to the turn and caught the same action from a different vantage point with my camera.