Loosen the bolt at the bottom of the distributor just enough to allow the movement cw and ccw about 10 degrees. If you clean the tab that the bolt goes through there are markings the middle is 0 degrees and if set up correctly that would be top dead center. Move the distributor each direction and you will notice the engine running smoother or rougher be careful not to make the engine knock. Just find the sweet spot and tighten the bolt (no need to over tighten), no need to us a timing light, some engines do not have a scale on the timing chain cover just use the little bit of adjustment at the distributor.