How bad is it to have a cracked valve cover on an old american V8 engine?”
There is oil coming up into the top of your valve train to lubricate it and the only thing the valve covers really do is prevent oil from spraying all over the place. If the crack isn’t leaking oil the gasket may still be good underneath and you could leave it alone for the time being. The worst thing that could happen… oil will leak out over your exhause manifold (or headers) and smoke and while you drive the smoke could come into your passenger compartment. If the leak is a lot… and it shouldn’t be since the oil there isn’t even under pressure… you could lose oil, maybe not notice that your engine is low on oil. That wouldn’t be good for your engine. Just buy a set of valve covers to replace them… www.summitracing.com or www.jegs.com … it is something you can do yourself. Make sure the new covers come with gaskets or buy those too.
