i have a 80 el camino with v6 with 400,000 miles still runs and cranks right up even when its cold.now i have 350 partially built crate motor coming in like in two weeks it should take me about a month to build it just right.well the v6 has a blown head gasket it has water in the oil i did a oil change i flushed the radiator did a tune up i need it to last at least a month or two.just for now. when i crank it up and i punch the gas some times it bogs out even some times back fires in the carb i put a fuel filter and still does it.i just want to know why?