Weak ignition comes from coils giving out due to age or heat, dirty or worn points, bad condenser, worn distributor, old wires to the coil, worn ignition switch, pretty much anything to do with engine electrical. Start with the basic's, distributor tune up. Then work back to the coil, and from there back to the ignition switch. Check wires and terminals and any contact points. Also, be sure the ignition switch is providing full battery voltage to the ignition circuit. For testing, you can wire straight from battery to the coil, bypassing the whole key circuit. Late timing effects the fuel burn in the cylinders so check that while you are at it. A little advanced will help. Short drives with the resister wires bypassed to the coil will not burn out the points, may over a long period it would, but not short tests. This will provide maximum voltage to the coil.
Joe
