Remove the thermostat fill the block up all the way with coolant with the lower radiator hose installed . Then reinstall the thermostat housing and upper hose . Top off the radiator and run a 10lb cap . This will help to keep your engine from over heating . By filling the block there will be no air pockets . Now you can run your engine 1600rpm for 15 min to break in your cam . When you first start it check good for any leaks . If you had a carb that you know worked good run it for now . This way you sould not have any problems keeping the engine running .