Those articles have some good info but also one thing that is totally wrong. I cut the first page out as all in it is correct. The incorrect part is right at the top of the middle column. He states "Advance cans are adjustable. Insert a 3/32" allen wrench through the vacuum advance nipple. You'll feel it lock in. Turning counterclockwise retards, clockwise advances timing". The vacuum advance is adjustable but the adjustment is just a spring that affects how much vacuum it takes to pull the can in so it does not affect how much timing the can produces. There is a fixed amount of timing advance in the can. With this adjustment you can tailor how fast the vacuum advance timing will come in and that's it.