Heres a picture of some of the sludge I removed out of an original 38 engine that sat 45 years. Cleaned it good with diesel fuel, replaced the standard mains and rod bearing. The original bearings showed very little wear. Did the MMO oil job on it, checked the oil pressure and compression and they were good. Some of the valves are 1 or 2 thousanths wide so I will reseat them. G.M.