I have a 235 in a 56' 4400 truck and I'm going to adjust the timing for the first time with a vacuum gauge. Mine also has a Pertronix in the stock distributor. The only vacuum port I have from the intake manifold runs to the vacuum wipers and the Hydravac. Before I screw this up, here are my questions:

Do I unhook the Hydravac and wiper connection and hook the vacuum gauge directly into the intake?

Do I disconnect the vacuum advance that runs from the distributor to the carburetor? If so, should I plug it at the carb until the adjustment is complete?

Thanks for your help and advice.

1956 Chevrolet 4400
1955 Chris Craft Sportsman
1953 Chevy 4400 (patiently waiting its turn)
1950 Farmall Cub (my great-granddad's tractor)
1948 John Deere M (wife's great-granddad's tractor)