new motor blues

what is the timing at? all small blocks advance their timing by turning distributor counterclockwise(against firing order). it may ping top end because your total centrifigal advance is coming in too fast or the curve is too wide. for now, tune it without the vac advance hooked up. change the plug(s) as needed. set the carb at about 2 turns out. what kind of carb? is your vac advance on a timed port or on a constant port?