Most of the candidates who attempted this question did not draw the valve timing diagram. Some who drew it did not use the required instrument. Only one centre performed well throughout the country. The correct diagram is shown below.

Part (b) of the question was not also well answered by the candidates. The required working statement for each is as follows;
(b)(i)   Valve overlap =6' +5'= 11'.
 (ii) Total period the inlet valve remained closed after bottom dead centre
   =360' _  (6'+180'+35')             
           =360' _ 221'                                                        
          =139'.
(b) (ii) Total period the exhaust valve was opened during the operation = 38' + 180' +5'
                                                                                                                                = 223'