My last winter I didn't run antifreeze. I just pumped it up as instructed, opened the blue plugs on either side of the engine to drain the remaining water...Oh I did the two cycle thingy in the fuel filter and ran fuel stabilizer while I was flushing. Never had a problem, made it through a CT winter like a champ. If my next boat has a 496, I'll do the same thing.

Thanks guys,, I was pretty sure I was safe,,,, I always warmed up my old 454 completely before running the anti-freeze, drained the block ran the anti-freeze, and drained again,, I wanted to be 110% sure.. This time around w/ the H.O. I wasn't able to warm it up completely, but pumped up the system, then ran the anti-freeze, then pumped up the sytem again,, just wanted to be sure the anti-freeze would make it through the entire raw water / heat exchanger,, seems like I am a.o.k..

pump it up and let drain, then crank the engine for 1 or 2 seconds ,(do not let it start) to pump out the remaining water in the sea water pump

Seawater pump has a valve you can open to drain the residual water out. That's another beauty of these closed loop motors.

Where is the seawater valve located??