I hear tell you have to do some clean out of the old coolant passages before you can add a closed coolant system ??? because if you add antifreeze to rust it will clog-up the system, is this so,and if so what is the procedure ??? the 427 engines were ran in fresh water,but they are 1971 twins,so please advise. Cause I plan on using this boat in saltwater,ounce of prevention and all that.
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