American Motor's first V8 engine debuted having 250 CID in '56, then 327 CID in '57. Production of the 250 ceased and a new 287 CID version replaced it in 1963. All these engines share common external dimensions, light weight - about - forged crankshaft and rods, as well as most other parts. The stroke for all Gen-1 V8s is . Engine displacement was a factor of the bore: the has a bore, , and the a bore. A number indicating the bore size is cast on the top of the engine block's flywheel housing immediately behind the right bank cylinder head. The block features a deep skirt where the casting extends below the crankshaft centerline, forming a very rigid crankcase gallery. The oil system feeds a central gallery to the cam and crankshaft first from front to rear, and then dividing at the front to feed the two lifter galleries from front to rear. From the rear of the two lifter galleries oil is then supplied up to the two rocker arm shafts which serve as galleries to lubricate the valvetrain. The fore and aft direction changes are designed to eliminate stale oil areas which tend to form sludge deposits.