how to adjust vacuum advance

With the vacuum connected you should have about 50* at about 3000rpm.

Without vacuum, you should have about 34* total at around 3000rpm by turning your dist in small increments.. Once you get 34*, bring it back to idle and see what you get. You should be between 12* to 18*.

If you can't achieve these kind of numbers, your dist will need to be recurved.

Once you get 34* total you can adjust the vaccum from there with the allen wrench in the vac pod.

you don't want any ping whatsoever.

Your plug gap seems excessive. I would not exceed 38 thou gap.

Jim