<VV> Broken valve seats

[Clark Hartzel]

How do pieces of a broken valve seat get into other cylinders?  On the
intake stroke the piston is sucking air into the cylinder and on the exhaust
stroke it goes out the exhaust tube.  Sounds impossible that a piece of
steel could be blown into another cylinder when the intake valve is closed.
Unless it happens at the overlap period when both valves might be open a
small amount.
Clark Hartzel