When the retard correction of the ignition timing to suppress knock is small, the deviance of the valve overlap amount from the optimum value due to that retard correction of the ignition timing is also small so the deviation of the valve overlap amount from the optimum value at {TAIL ~ this time} does not pose {HEAD ~ a problem} 
When the retard correction of the ignition timing to suppress knock is small , the deviance of the valve overlap amount from the optimum value due to that retard correction of the ignition timing is also small so the deviation of the valve overlap amount from the optimum value at { TAIL ~ this time } does not pose { HEAD ~ a problem }
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