not a 351, but 302 problem i need answered

[Jeff Chambers]

Valve stem seals won't show anything in a leak-down or compression check. If the seals are bad, or have worked themselves off the guide, when the valve is open at idle and part throttle the engine vacuum will pull oil down past the valve stem and into cylinder, especially on the intake side. Some racers will actually run without any exhaust valve stem seals since there's no real mechanism to pull the oil into the cylinder from those locations. If the car smokes badly at idle and part throttle, I'd suspect the valve stem seals.