There are many things to determine your timing. If you have vacuum advance,compression ratio,grade of gas your using,camshaft overlap,etc.The simplist way is to mark your harmonic balancer at 36 degress BTDC[before top dead center] Now disconnect the vacuum line to the distributor and plug it.Rev the engine to 2,500 rpm and check timing with the timing light.Set the advance to the 36 degree mark.This is a good starting point.I would put an adjustable vacuum advance module [accel] and adjust it for 10 degrees vacuum advance extra at idle,when the throttle is opened the vacuum drops and the vacuum advance dissapears and you run on mechanical advance only. The vacuum advance will give much better gas mileage and drivability. if you have aluminum heads you can run 2 to 4 degrees more timing.
Perry.
