Quick radiator flush-how much fluid to add?

[billschroeder5842]

I'm doing a quick radiator flush on my '69. I've drained the radiator, let the engine run to temp, circulate and kept adding water to flush it out. The water is pretty clean but not perfect--must be the years of gunk in the water jackets!

Now, the question....the system has been flushed enough that what remains in the engine and the heater core is pure water. How much anti-freeze do I put in the radiator? My big issue is overheating and not freezing as I live in Texas. Oh, I do have a 165 degree thermostat installed in my 383.

Thanks!

[Just 6T9 CHGR]

I would get 2 gallons of the pre mixed stuff & fill it up.  A bottle of Redline Watter Wetter is a good choice as well