yes sometimes...Ive been doing spring combos to get the curve to fit my app. Actually pinged at 3000 , hard acceleration. Had some detonating going on. I am wondering if im not talking the vac. advance into consideration.I just set up the mech. advance to open quickest and is set to 18*which should be at full advance at 1800 -2000 rpm.( right around stall speed). Dat good?