oil in valve cover is full but dip stick shows 1 quart down

If you meen the valve cover is full of oil,then the returns must be clogged.That happens from not keeping up with oil changes.They must be cleaned very carefully.

This is a sign of some serious engine sludge! A complete teardown of the engine will need to be done, and the block, oil pan, valve covers, oil passages, oil pickup screen, and other assorted areas cleaned of the sludge and buildup inside the engine block.

I've seen this many time before..... it is usually caused from lack of oil changes which cause sludge to plug the drains in the head.