Tinker with the timing until you reach the point when it is as advanced as possible without knocking.
Spray some wd 40 on the levers and linkages outside the carburetor body.
Add fuel system cleaner additive
Check if the vacuum hoses are connected to the correct place.
Check with timing light whether the timing advance mechanism is working.
If the car has done more than 100,000 km then check coil and plug wires with multimeter, visually check distributor cap and rotor