I've got a couple of cold nights coming up and I wanted to at least drain the block for the next few days ( I plan to take it back out one more time before a full winterization.) This is my first winter with this 496 mag so I figured out the pump system and did that, then pulled the 3 drain plugs (are there more?) only about 2-3 cups of water came out though. Should there be more or does that sound about right? Again, this is just temporary to get me through the next 3 days (one night is 26 and the next is 30)?? Thanks guys.

Poke a screwdriver in the hole and get the crud out of the way of the drain.

You only got 2 - 3 cups out when you pumped air into the system or you got plenty of water out when you pumped the system but only a little bit more when you pulled the plugs? You should get a ton of water when you pressurize the system. I get just a few drops at most when I pull the blue plugs after draining the system with the pump.

i left the plugs in and pumped the system until the water stopped flowing out and the two green plugs popped out on the schrader valve. then i took the 4 blue plugs out but nothing more drained. it was probably more than 3 cups but it certainly wasn't a "ton"

If you only got about 3 cups of water total then you definitely have some obstructions in the drains.

dunno...i stuck a pick in the drains with the plugs out and there was nothing there. when i pumped up the system and watched the water drain...it just went until it tapered off then quit. did not stop abruptly like something was blocking drainage.

maybe i'm mis-judging the amount of water but once it was all drained, it still was not deep enough in the bilge for the pump to pick it up or to run out the rear plug hole. it was covering the whole bottom of the bilge but I had to tilt the trailer to get it to drain out.

I have 454 mags, but when I pull the blue plugs, if "nothing" comes out, then I stick something in there until I clear the jam and water flows. There should be some water drain.. couple cups from each hole at least. You have closed cooling so I am not sure what portions are still running fresh water, but I should still have more as mine are all freshwater cooled.

this might be a stupid question (forgive me I'm still a newb) but could I turn the engine over a few times or run it for a few seconds to purge what could possibly be left?

My last boat had a 496HO. The drains for the pump out system are pretty close to the lowest point of the motor (the parts that are flowing sea water). After using the "pump out" system not a whole lot of water would come out when I pulled the blue plugs.

I would leave the pump system open (green plugs up) and leave all the blue plugs out until you are ready to use the boat again.

No, do not run it. That's not going to help anything. You should see 2-3 gallons drain out of the engine block when you use the pump. Remember, the air pump system does not REPLACE the water. It only opens two actuator valves; one fore and one aft. Then removing the blue plugs might yield an additional couple cups of water.

Couple things:
Don't bother with that tiny pump. Use a 12V air compressor. You can't over-pressurize it with a low volume pump like a 12V compressor. The pop-off valve will release when it get's to proper air pressure.
The air pressure system does NOT drain out all of the water. It's only designed to extend your boating season. If you want 100% freeze protection, you need to run antifreeze through the sea-water side of the engine, just like you would any other engine without closed cooling, You do NOT want to half-ass this; especially if you are in prolonged deep freezing weather.