Tony Let me throw my 2 cents in. If during the engine rebuild, if the clyinders were bored you might have honing residue that has clogged the oil return holes. If they are clogged, oil cannot drain back into the crankcase. If this happens, it can accumulate in the cylinder head and over lubricate the valve stems causing oil consumption. When you say you can't see it smoke, do you mean just on start up?