See what I meant about the booster being full..

Anyway, if the timing is too far advanced , the engine will ping.
A good test if one does not have a timing laght is to go up a slight hill in top gear at 20 MPH and apply the gas without having the car downshift.. ..........listen for engine ping..if there is some , back off the advance until there is none...that will give you approx timing... it actually is a better way to timing the car than a light b/c you are timing the engine to max power for that engines compression. and gas being used. The engine will tell you what it likes better than a chart.
My 190sl actually has a cable/knob on the dash that turns the distributor and lets the driver time the car for different octane ratings/conditions in the same way...