http://www.crowleymarine.com/support/tech_articles/omc-cobra-winterization-procedure.html
First, the engine oil and filter should be changes, as well as the outdrive gear oil. Be sure to follow the procedure exactly as it is described there, that is the right way to do it...
Then the engine is warmed up and fogged through the carb, the idea is to stall it but it may not stall, you may need to get an assistant to shut it off so it does not burn off all the fogging oil.
Although the 460 (7.5 liter) Ford is not listed in this document, they are all pretty similar. There are 2 drains for the engine block, one on each side, use a small adjustable wrench to loosen them (normal size ones won't usually fit in the tight space under there) and a pick or thin screwdriver to poke the holes to make sure both sides drain. The port side drain is toward the rear of the block and the starboard side one is also toward the rear, under the P/S cooler. I like to put OMC gasket sealer on the threads of all the metal drain plugs.
Then disconnect the bottom end of the large hose at the engine circulation pump, that drains a good amount of water. Drain both exhaust manifolds the same way, they use a rubber cap on the end of the manifold you just have to remove the hose clamp to drain, then poke the holes. The P/S cooler is accessible on the 460s and you can drain it via a plug on the bottom end. I also disconnect the hose that leads up from it to the thermo housing then hold it down to drain.
There are 3 drains on the pivot housing of the outdrive (2 on starboard, 1 on port), the one that usually drains water is on the port side, remove the plug and poke the hole, water should come out...I like to fill that hose from the themo housing to the transom with -100, this will flush out the hose, transom hose and the impeller housing, some AF may come out that drain hole in the pivot housing, and out of the drive water intakes. After it drains, put some OMC gasket sealer on the threads and replace the drain plugs. On the starboard side, the upper one usually does not drain water but check anyway. The lower one is a drain for the pocket where the shifter bellcrank sits, there should not be water there but if there is, let it drain. If you get water there, the drive should be removed and that area should be cleaned out and packed with OMC triple guard grease to keep water out. This you may prefer to leave to a mechanic, but pulling the drive should also be done at the end of each season.
