Sorry, I don't have a picture.
At each end of the cylinder heads there are holes to allow oil to drain back to the oil pan. One hole at each end, so there are a total of four.
In addition, there are other ways for the oil to drain back. There are other holes and slots - like where the pushrods go through the head - that also can contribute to oil drain back.
The holes vary in size depending on the particular head but generally are about the size of a nickel or a quarter.
The oil the gets pumped up the pushrods to oil the rockers and cool the springs then drains toward the front and rear of the heads, then down through those coin sized holes, into the lifter valley (where the lifters) are and then through more holes until it returns to the oil pan.
Unless your engine has very, very high mileage and received ****-poor maintenance, I seriously doubt the drain back holes are blocked. You'd have to REALLY neglect oil change intervals to cause enough crud to build up to block the drain back holes.
Blue smoke at start up is most often caused by bad/worn valve stem seals.
Last edited by JakeJr; 08-30-2004 at 10:15 AM.