408 tuning with a Wideband sensor

crackedback said

What vacuum does it pull on the highway?

You may need a higher number power valve so it opens earlier.

I'd put the timing back to where you had it and tune it there. If it's not pinging under load, run it there.

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I did some vacuum measurements today. At idle it pulls between 5-7 depending on whether or not the electric fans are running. Most cruising situations yield around 13. The car is still quite rich at idle = mid 13s. Low RPM cruise (less than 2500 is in the mid 12s. It leans up a little when I get closer to 3000RPM. I'm guessing the mains are starting to come in at that point.