very slow spark they traval at the speed of light
do you mean weak spark.well first things first
1 check ignition coil connections,and main coil ht lead, remove and refit them
2 check your dizzy cap and rotor arm for cracks and burn marks
3 check the crank sensor (its down by the crankshaft pulley 5 o clock position as you look at from the front)) make sure theres at least .5 to 1 mm between it and one of the 4 raised stubs on the pulley
4 check the multyplug connection remove and refit on the ignition amplifer,its behind the passenger side strut top and is bolted to an aluminium heatsink block which is secured to the inner wing
i could go on and on but see how you get on aith those for the moment
you could be lucky and it might just be a worn out coil so try swap one for a good one and see if it helps