The combination of wires and plugs would cause a problem. Change the plugs first. I would use W7DC or W7DCO plugs to start with. If you run the car much out on the road, go with W6DC (or "0s"). The Euro M110 engine will run real hot in that area and never rattle (spark knock) until too late. A hemisherical combustion chamber will take lots of advance (about 44 degrees) but the temperature will be really high.
If that doesn't help get some 1K resistor ends.
Randy(ignition is my life) D.