Yes,there may be two or four.Put a vacuum gauge on a manifold vacuum port.Turn one of the screws in a quarter turn while watching the gauge.If the vacuum drops stop and turn the screw the other way.Rotate around all the screws until the vacuum gauge is at the highest reading you can get.Then you can play with your timing again.You said you have 10 degrees now,try twelve.If it starts good and does not ping try a little more.Just don't go past 36 total.If you have an adjustable vacuum advance you can really play with it.