Put in the 2 pounds of baking soda and 4 gallons of water about 6pm. Let it run for about an hour in the driveway. Temp stabilized at around 165 in the thermostat housing (still no thermostat installed) and 170 at the rear of the head at a fast idle. Then adjusted the idle speed to give 4 mph in 2nd gear of my SM420 transmission. Let the idle speed get me to the gate out of the subdivision, just under 1 mile, simulating parade speed. The temperature may have varied 5 degrees max. Air temp was 94 to 92 degrees.

I'm planning to leave the baking soda in the truck overnight, then crank it up for an hour of idling in the morning. Then another slow trip out of the subdivision followed by 10 miles or so of 40-60 mph driving.

Hopefully Jerry will check in with a recipe for the TSP flush by then.

'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.