Playing with a big block, chasing an off idle stumble. While checking the distributor, I noticed that the timing would retard as much as 8 degrees when I snapped the throttle. Made sure that the vacuum advance was disconnected to prevent false readings. Still the same result. Timing isn't erratic. In fact it's pretty solid while ramping up the rpm to full advance. Was just wondering if anyone ever saw a momentary timing retard during acceleration before.