Bob, check to make sure the PCV valve is clean, and that the valve inside will "rattle" when you shake it. A valve that is gummed up, or otherwise restricted will cause the crankcase pressures to not be relieved. Also make sure that there is some way for fresh air to get into the engine, so the PCV valve can work. Check the "filter cap", and be sure it is clean. Make sure that there is a good vacuum source for the PCV valve, too. The carb fitting may be gummed up, or restricted, and not allowing full vac. to the PCV.
If the PCV valve is clean, and it has a breather of some sort that is clean, but there is still enough crankcase pressure to blow the dipstick up, or the PCV valve out of the valve cover, you may be looking at a rebuild soon...
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Joel Adams
C3VR Lifetime Member #56
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"