neswes,
Going to hotter spark plugs will not cure your rich fuel problem; it will only make the spark plugs look better. If you are seeing blue smoke, you have an oil burning matter to deal with; black smoke indicates a rich fuel condition. I doubt that crankcase pressure is the cause of oil burning. That is a possibility, but if that is the case, you should see oil leakage from seals and gaskets. Are all your spark plugs the same color? A good color is light tan to off-white, depending on the age of the plugs. Dark tan to brown indicates the spark plug temperature is a little too cold for your operating conditions. Possibilities for that are spark plug heat range is too cold, slightly rich fuel mixture, and slight oil burning. Spark plugs that are black but dry (sooty) are showing a more serious rich fuel condition. Black, crusty and wet-looking usually are the result of oil burning. And these conditions all depend on the mileage on the plugs- greater mileage gives better indications. From your description, it sounds like you have oil burning to deal with. With 3000 miles on the engine after a rebuild, the rings should be seated, but depending on the ring material, oil you are using, and the ring fit in the cylinders, the rings may take a little longer to seal properly. If your engine is a 1959 or later, the oil passage for the rocker arms is a passage inside the block and into the head. The head gasket was known to leak oil into the two center cylinders on those engines, although that problem was fairly infrequent. If your engine has the older oil tube that runs outside the block (but inside the side cover), and through a hole in head to the rocker arms, you won't have the head gasket possibility. Other possibilities include valve stem oil seals leaking (or maybe not installed, as would happen occasionally in the past), and oil dilution from the fuel pump leaking fuel into the crankcase (check your oil for the smell of gasoline and/or the oil level being too high). Anyway, running hotter spark plugs will only make your spark plugs look better, without correcting anything. After all this, my first thought, after checking for oil dilution, is to run the truck for a couple of thousand miles more and see if the oil smoke stops.
Hope this helps.
Harvester
