This is the Operating Manual Packard Marine Engine 4M-2500 Types W7 through W17 for PT Boats and provides operating instructions, an explanation of all major components, and maintenance procedures. This is not a shop overhaul manual. Since both PT boats and the 85 ft. crash boat used the Packard 4M-2500, the information should apply to both boats. This digital copy of National Archives and Record Administration microfilm provided courtesy of Al Ross and Richard Washicheck of The PT Boat Forum.