3/8" ? How in the hell is the engine not toasted? Your pistons, rods, main caps, cam chain and sprocket, oil pump and many other miscellaneous parts would be destroyed if your crank moved back and forth 3/8" at over 2000 rpm. The thrust bearing on the crank shaft isn't even 3/8" thick. The only way your crank could move that far is if the thrust surface of the main caps and the crank shaft wore each other out. The block, crankshaft and all short block pieces would be toast.