A Hammer, a big farkin Hammer. One that you need Ape Arms to swing. Personally, I recommend a 3Lb Sledge, though others will tell you a Dead Blow is the way to go. Either way this tool will unquestionably help in speeding you through disassembly of the 400 motor. Got to a point where a bolt or screw is stuck? Bring out the Hammer. Thingamabob won't come apart? Bring out the Hammer. Don't quite understand the shop manual? Bring out the Hammer. Smack your thumb squarely with the Hammer? Throw it at the wall, it's quite the versatile tool.