thats a sign that it wants more advance. the way i was told to do mine (and it worked wonders) was to advance the timing 2* initial with the engine at full operating temp until it has a hard start or kicking back on the starter problem and then back it up 2*. that is what the engine wants for initial timing. they you need to limit the mech. advance in the dizzy to what ever your total desired timing is. then you adjust the curve so it is in full by your desired rpm.
my combo likes 26* initial
36* total all in by 2600rpm.
i have a 4000 stall so having my advance all in off idle is not necessary.