Vacuum advance issue

Dan Georgino said

It's a 360, they all have vacuum advance, not an old engine, it replaced the 340. I'm going by what he said, and that was it's pinging, so he is probably getting way past the 34 with the vacuum advance, so he needs to be all in with the vacuum advance hooked up. He also probably has it hooked up to the wrong vacuum port, or wrong gasket on the carb. He could have also put to light of springs for the centrifugal weights and the come on way to quick. He could also stick a Allen wrench into the snorkel of the vacuum advance and have it come on later. Many possibilities.

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At light load cruise, you may have more than 34° advance without detonation or ping. Light load cruise has a less dense mixture which burns slower. This requires more lead for economy.
As the throttle is stepped on or opened, the manifold vacuum drops and the vacuum advance drops off. The cylinder density has increased, putting more air and fuel molecules in close proximity for the chemical process known as combustion to take place. This increases the rate of that reaction or burn.
Remember that the intent of tuning centrifugal advance and vacuum advance is to develop maximum cylinder pressure about 10° to 15° ATDC.
From reading the OP, my opinion is the vacuum line is connected to a ported vacuum source. I come by this by the statement that as soon as the throttle is stepped on it starts detonating like a woodpecker on crack. The rest of discussion about weight springs and adjusting the vacuum advance (if it is adjustable) is all a matter of tuning how each reacts.