IME, retarded timing will often start and idle very well, will not backfire and lack power as RPM increases.
coincidentally, i just replaced my old distributor. i had concluded that it was failing to advance the timing properly, possibly due to binding weights.
power was lacking as the RPM increased due to misfires. the differing symptoms, yours simply lacking power, and mine misfiring, could be attributed to the richness of the mixtures between my carb and yours.....possibly.
