I pulled off my valve covers to replace the leaky gaskets (no small job on an '85) and had gobs of crud in and around the rocker arms. The oil drain back holes (i assume that's what they are) were all completely occluded. There are 4 of these holes, one at each end of the head. I thoroughly cleaned these out as with the rest of the top of the head and installed the new gaskets. Do these provide oil to the rocker arms, or just allow it to drain back to the crankcase? In any case I hope to have better oil distribution now. I have heard that on an old high mileage engine like this 305 you can put a quart of tranny fluid or marvel mystery oil in it for 1,000 miles or so and it goes a long way in cleaning some of this sludge. any other suggestions? "who dares wins"