I have timed my 41 and it is running really good, it is purring after two valve adjustments. The question I have is when I hit the throttle the engine advances very quickly. is this because I timed the engine , off the ball, with the vacummn advance disconnected , does the timing of the engine require the vacummn advance to be connected or disconnected? Or does it make no difference in the fast pick up of the throttle advance? thanks doug