Looking for a little help from my friends. I just replaced the head on my 1991 f150 4.9 with a re-manufactured one. Now I have a rattle in the top of the motor. Just checked the clearence from the top of the valve stem to the bottom of the rockerarm with the lifters compressed. And the cyclinder at TDC. The book says it should be within 0.125 to 0.175 but I'm only showing a clearence of 0.071 does this mean that I need shorter pushrods and could this be the cause of the rattle?