has anyone ever had this problem or even heard of it? a month ago i bought an 89 sc with 109*** miles from a kid who blew it up doing a power brake burnout. the valve covers blew apart. he replaced the covers but did it again. it doesnt knock and will only run if you give it some gas but seems to backfire through the valve covers. i am gonna tear it down next weekend and was wondering what i should expect to find. any suggestions?