How do you set the dwell on a 350?

Dwell is the length of time the points are closed and the coil saturates.... adjusting the dwell changes the timing so do dwell first. Be sure to apply lube to point block. Connect a suitable dwell meter to the car. Putting an Allen wrench thru the side window on the distributor and into the recepticle on the points and turning it, raises it or lowers it. When you achieve the correct reading, close the window. Then you must adjust your timing. 350's like 8 to 10 btc.