Yesterday flushed the radiator and system twice using distilled water. Got some 'stop leak' debris from the catch tank, but none found from engine. Refilled using Evans waterless coolant. Interesting stuff, that Evans.. with fan disconnected, could not get coolant boil over, temperature needle 1/2 width past top of hot zone when I terminated the burp run. I did get quiet a bit of bubbly action in the catch tank, and the amount of coolant added is very very close to the FSM spec capacity, post burp. Here's a little video of the coolant change and flush.. carb sync too.
2021-01-11 Carb Sync, Rad Flush, Evans Burp from dcarver220b on Vimeo.