THANKS PETER FOR YOUR RESPOND . IN FACT WE DIDNT WANT TO TAKE A CHANCE SO WE REPLACED THE LIFTERS IN THE SAME TIME , AND THE OLD VALVES WERE NOT BENT BECAUSE THE LIFTERS HOUSING ABSORBED THE IMPACKT,BUT WE CHANGED THE VALVES AS THEY COME WITH THE HEAD ANYWAY. MAYBE THE NEW LIFTERS NEED TO BE COLLAPSED ? ALI.