Your numbers don't make good nonsense! The total vacuum advance should not be more than about 10-12 degrees, and MUST BE DISABLED before attempting to measure a centrifugal advance curve. Centrifugal advance should begin somewhere around 1,000-1,200 RPM, and should be complete somewhere around 2,500 RPM with 25 degrees or so of advance over the initial setting. Depending on which flywheel you have, the BB will be somewhere in the range of 0 to 5 degrees before top dead center. If the initial plus centrifugal advance totals more than 35-36 degrees at cruise RPM, you're trying to run the engine backwards. Vacuum advance can add up to 10-12 degrees, but only at light throttle cruise conditions.

A variation of 12 degrees of dwell means you've got worn out bushings in your distributor, or your dwell meter is lying to you.
Jerry

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