Question about flushing out my cooling system.

First I know to take old tstat out, install housing back on, put hose in the radiator with the drain plug out and let the car run until completely clear. The questions are 1. once it's cleared can i shut the hose off and allow the car to run very briefly to get any remaining water out, or does this not help at all? This leads to 2. Will there be water remaining in the block, and if so will that hurt anything after installing new coolant?
i bought one of those nozzles that fit on the end of the hose and you twist it to make it go from like a pressure washer to a soft dispersed flow. It is only like 5/8 round and it works extremely well as I plug it into the various hoses and run it full blast until I see clear water and then fill it all up idle it and let it all drtain and then fill it back up with coolant. I was able to get a shitload of sludge out of the radiator. It was so thick when I took out the drain plug nothing came out and I had to use a screwdriver to coax it out. Car runs considerably cooler now too!


