Will,
that valve is called the oil distributor valve. When the motor is first starting, the valve is closed and oil does not flow to the rockers or the connecting rod dipper sprayers. As the pressure builds up, the valve opens and allows flow to both. If that valve is not opening, the rods will not get lubricated properly. You can check the passgeway to the rocker line by taking the small plate off and removing the distributor valve. You can then fish through the rear hole in the valve cavity over to where the line is attached. This operation does not involve removing the pan.
