HEI upgrade?

RedFish said

Actually neither dark blue or brown are ever cold. If they were a backfire could result.
Owners who dont quite understand electrical will freak out if they go to the ignition switch connector and find approx. 7 volts on the brown wire while the engine is running.

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The 7 volts is feedback coming from the ballast. It doesn't do a thing as the switch contacts are open. How does this prevent backfire?

I don't know about "all years" but at the very least "some years," the dark blue most certainly goes cold when the key is in "start."