454 timing and tune

[CJ_Chevy]

Well ive been spending a little time on tuning my truck now that all the vacuum lines are connected. its a factory lf8 with ac and th-400. the engine was completely rebuilt, put speed pro domed pistons, comp 260h cam. everything was redone, in the valve train as well. im running on 93 pump. emissions have all been deleted.

I was setting the timing and i set the intial close to factory spec, 8* but when i would go to wot, the carb would back fire and sometimes shoot a flame. i figured it was a timing issue so i advanced the timing up till it would wot without sputtering or backfiring. i checked the timing afterwards and its around 12*. that seems reasonable to me. now when i was using the factory port on the back of the carb for the timing advance, the idle would increase quite a bit. i could not get the idle to come down to a normal level. so i plugged that port and hooked the advanced up to the ported vacuum port on the front passanger side of the carb. this setup seems to work well, but i am not 100% sure because the truck isnt done and i cant take it for a test drive.

the only thing that seems a little off is that the idle still seems a bit high, and it kicks when putting it into gear. tranny was rebuilt and has a mild shift kit. i put new springs on the throttle lever and it doesnt seem to pull the carb shut all the way. i disassembled the carb and got a rebuild kit for the factory settings.

does this sound sort or normal? or do i need to keep the timing back more around 8*, or the factory rebuild kit came with too small of a accell pump? any thoughts would be appreciated.