Remove foreign object from engine cylinder

If you are talking wooden/graphite pencil I would not be too concerned, it will leave via the exhaust port pretty quickly with the engine running. The materials in a pencil are not hard enough to cause any damage. I don’t believe the wedge heads of a Corvair engine pose any risk of piston energy being transferred to the actual valve heads either. Many more modern designs with hemispherical head and canted valve configurations could pose a risk with soft materials like pencil fragments becoming captured under an open valve lip as it closes leading to piston valve interference damage. I don’t expect that could happen with the Corvair engine though. If you are OCD you might decide to dismantle or try using a borescope and a flexible tool to grab and extract the piece(s). Back in the day (1970’s) we routinely removed fragments of VW accelerator pump arms that fell into those engines from the Solex carburetors (a common failure mode). The fix was pouring about 16 ounces of tap water down the carburetor at fairly high RPMS while the engine complained very loudly at the mistreatment. Eventually the small brass parts would break free and exit via the exhaust ports and the loud noise would go away.