As long as you keep running a points system, you will need to become a habitual timing checker/adjuster.They just don't stay in tune all that long. If you can get a hold of a good old fashioned tach and dwell meter and timing light then it is easy to do; use white-out typewriter correction fluid to highlight your timing mark on the crank pulley.
The gap size on the points effects the dwell, which is the amount of time the points stay closed between sparks. A long dwell time allows better coil saturation which in turn gives you a hotter spark at high rpm's, but it also causes excessive coil saturation at low rpms, which can lead to overheated coils and decreased coil life.And yes, you will effect the timing as you adjust the points gap. You shouldn't be guessing at this; the correct way to do the job is to set the points, then check and adjust the timing and check the dwell. If you don't have a dwell meter then set the points gap in the middle of the range and make sure the timing is correct.Adjusting the idle should come last, unless the car is idling so fast that it is causing the centrifugal advance to start working.
There are several easy ways to convert your ignition system to a much more reliable and higher voltage electronic system. Pertronix makes a breakerless electronic system that simply replaces the points and uses your existing distributor, or you can use the electronic distributors from a 280Z or ZX. These distributors are much more reliable; they essentially never come out of tune, and the control modules automatically adjust dwell. They also operate at twice the voltage of a points system, which gives you a much hotter spark.
