[pm220b]

You should loosen the hold down screw while the engine is off just for safety but keep the screw snug enough so you can just turn the distributor by hand but not too loose because you dont want it moving around on its own. Dont wory about Top dead or anything you can turn it while the engine is running at idle and as you slowly turn it you will notice the engine running better or worse. Counter clock wise advances and clockwise retards. If you do have a timing light put a white chalk mark on the zero on the Crank shaft damper (harmonic balancer)then attach the timing light to # 1 spark plug wire and as you turn the dist you will see the degrees that the white mark is from the pointer but if you dont have a light just time it by ear by turning the dist slowly as it idles. till it sounds better. Leave it just snug and road test. You might have to stop on side of road and turn it back a little or forward more. Best to move it a little at a time till you find what works best for you.