A little note concerning smoke on startup, and diagnosing a "smoking" engine. Oil always burns as a blue to blue-gray smoke, never white. White smoke is always fuel or water. Pure water will disappear immediately or almost immediately (depending upon ambient temperature), and coolant will linger, and usually smells sweet. It will also leave a film on the inside of the exhaust pipe. White smoke that dissipates slowly, or not at all, and smells of fuel, or has no smell, is likely fuel. This has a bearing upon Willard's hot restart problem. That the engine will only start with the accelerator pedal floored, and it belches white smoke when it does start, indicates that the fuel in the carburetot is boiling out, and landing in the intake manifold. Fresh oil on a spark plug that is pulled from an engine that has just been shut down, indicates that the cylinder wasn't firing at all, and that there is likely no fuel in the cylinder, as it would wash down any oil, and smell of gasoline, if fuel was making it into the cylinder, and the spark plug not firing. When oil is burned during running, and it is constant, it is usually due to worn or stuck rings. When it is due to bad valve stem seals, a puff of smoke (blue) on startup, along with increased burning of oil (smoke returns or gets worse) when the engine is at higher speeds, and especially under high intake vacuum conditions. When stem seals are bad enough to foul plugs, the rings are usually suspect as well. A compression test will indicate whether the rings are involved in oil loss. If compression readings rise significantly upon squirting a little oil into the chambers, the rings are involved. When guides are loose, it usually shows up as a fluttering needle on the vacuum gauge, with no real change in performance associated with it. If the engine has vacuum reading flutter, good compression, and oil consumption that is usually most evident on startup, rebuild the heads. If there is no vacuum reading flutter, oil consumption mostly on startup, and good compression, then just replace the stem seals. My experience with air applied to a cylinder at TDC, has led me to positively stop the crank from turning with some physical means, before applying the air to the cylinder. Using string or rope is much more convenient on most engines, as it does not expand, thus turning the crank, and dropping the valve. A good rule to follow here is: Don't feed the entire string into the chamber! You want it to be as easy to retrieve as it was to install. Moving through the firing order is easiest, but involves switching sides with almost every cylinder. Not too bad, but can be a hassle. Don't laugh, but use a good quality rope or string, and not plastic. If you lose any fibers from a natural fiber rope, it will burn away. If you lose any plastic fibers, you are just playing with potential glue inside the engine. I have even used electrical wire for the job of holding the valves up, in a pinch. String is easier.
