Looking the motor over again, I notice the exhaust valve lash cap was missing and there was huge clearance there. I started to replace the lash cap, but noticed the action of the rocker wasn't smooth. I took the rocker box apart and saw the exh. pushrod wasn't sticking out as far as the intake. I then took the timing cover off and found the problem. The motor has roller rocker cam followers and the exh. roller spindle had broken and the roller was laying in the bottom of the case. This allowed the rocker to bear directly on the cam lobe and galled it up.
|Open hear surgary|
|the left (exh.) cam lobe worn by the rocker. Mark Gibson photo|