I have been fooled by point gap, the fibre block wears and you don't have any gap and the thunder is taken from the engine.
Do you have any loose plug wires?
if dwell and gap are fine along with timing, Get a clean rag, remove air cleaner, open the butterfly and build rpm, at a high, cover the air intake with the rag and keep the throttle open, this will choke the engine down when it slows, remove the rag and let it build rpm, repeat a few times and see if this backflushes the jets. Sometimes it is enough to get whole again.
