I was able to pull the engine out of my 420 tonight (thanks for everyone's advice on the previous belt tension issue). Now, I need to remove the PTO clutch/exhaust system, then intake manifold (in hopes of rebuilding the carb). I was able to remove the PTO armature, then the rotor. I now need to remove the key to get the remaining components of the clutch off so I can access the muffler bolt heads. The key seems pretty stuck in there. Reading other threads, it looks like the first step will be to pick up some penetrating oil tomorrow and get that working. Any other thoughts on tackling this?
Call boomer at boomersonanparts.com or the 2nd place is Onanparts.com get a replacement manifold. It is cast aluminum 2 piece manifold. It is subject to a lot of heat/vibration. Would not want any more to crumble and end up in the engine.