Two cylinders will be at TDC with the ball and pointer aligned, #1 and #6. Depending on which cylinder's valves are closed, one is at TDC on the compression stroke, and the other is at TDC between the exhaust and intake strokes. Look at the distributor rotor to see which cylinder is ready to fire. Once the BB is aligned, just turn the distributor housing clockwise until the points close, and then back it up CCW until they are barely open. The timing is set- - - -now it's just a matter of figuring out which cylinder needs the spark plug to fire. Some folks put a cork into both spark plug holes, and set the rotor to point toward the cylinder that pops the plug out as the engine is turned clockwise from the front to align the ball and pointer.
Jerry
