There are two adjustments on most stovebolt distributors. there is a narrow slot where the vacuum advance bolts to the block with degree markings known as an "Octane selector". It was used to fine-tune the distributor for varying grades of gasoline, not for initial timing. The other adjustment is a clamp that grabs the distributor housing, and allows for a wide range of adjustment (360 degrees, actually!). Center the octane selector at the zero mark, loosen the body clamp, and set the initial timing there.
There is a hole in the bellhousing just above the starter that has a pointer mounted in the center. There is a ball-shaped mark on the flywheel (sometimes called a "BB") which is aligned with the pointer with the engine stopped by turning the crankshaft. With the ball/pointer aligned and both valves closed on the #1 cylinder, turn the distributor housing clockwise until the points close, then turn the distributor CCW until the points BARELY open. Lock the clamp down. Use whatever distributor cap tower that the rotor aligns with as #1, and arrange the plug wires clockwise in order 1-5-3-6-2-4. Button everything up and start the engine.
Jerry
