Here is a write up I put together to attempt to help anyone who pulled their dizzy and now got a bit confused.
Mark the base of your distributor below the cap where #1 tower is on your distributor cap. Pull #1 spark plug. Insert finger in #1 spark plug hole.
Turn engine with socket and breaker bar until you feel a whoosh of air pushing past that finger in #1 cylinder. Remove finger and drop a long bladed screwdriver or wooden dowel into #1 cylinder.
Slowly bring #1 piston up to TDC. That is where #1 piston is at its highest point. You are now at TDC on the compression stroke of #1 piston.
Now check your timing marks. It should be at TDC also. Pull your distributor cap. Your rotor should be at or just before #1 tower of that mark you made noting the position of #1 tower on your distributor cap.
If not something is not right….obviously. That could be a jumped timing chain, or a bad distributor gear. If the timing marks are off but it runs fine then the most likely culprit is the harmonic balancer which is a two piece affair has had the outside layer ‘slip’ so the marks are off but the timing is correct.
If your rotor is not where it should be and everything else is OK slide the distributor up just enough to get the distributor drive gear past the cam drive gear to move the rotor into the correct position. Now before you slide the distributor back into the engine you need to back off the rotor position a little. Where you start is not where the rotor orientation will end up because of the helical cut gears. The distributor shaft will have to advance some clockwise because of that gear design to end up in the right position. If you leave the rotor on the distributor you will see that advancing movement.
Once you have that in right tighten down the distributor hold down bolt until it is snug but you can still turn the distributor if possible on your (older)engine. Slap on cap, and try to fire her up. You may need to move the distributor some if possible until she does fire up. Then set your timing to whatever the specs are, IF possible (older engines). On the newer engine timing is governed by the 'brain' and is not adjustable.
Do you know what was good about the good old days? I wasn't good, And I wasn't old!
Senators and Congressman should wear uniforms like NASCAR drivers so we could identify their corporate sponsors....