You shouldn't be playing with it, to find the "sweet spot" where it will run. You have to set it correctly.

Get the #1 cylinder to TDC on compression stroke. Place the distributor with the ROTOR pointing to the #1 mark on the pick up coil/cam sensor. It is important to get it as close to perfect as you can, unless you got access to a full scanner as described above. See picture below. Don't forget to place the plug wires in the correct locations and in the correct order.