Once burned a wee pie shape out of the #2 exhaust valve of a 250-6. Had a huge hole in the exhaust (several inches open) just below the manifold flange and that took 7 hours of sustained high RPM hyway (Toronto to Quebec City) to cause. Loss of exhaust back pressure will effectivly lean the engine out at hi RPM, but that's a big hole you're talking about. A gasket leak, or a manifold crack at reasonable revs shouldn't hurt anything. Is there a running 292 out there that DOESN'T have an exhaust leak??? What do they sound like?
Drive it!
