about 6 thousand miles ago I had a big cam put in my car along with big springs and retainers. Sometimes if I don't let the car warm up even in the summer after about 5 miles I get a heavy knock on the left side like a lifter banging away. It goes away after I drive it a little while like its pumping oil up but it sounds ungodly. my specs are 98 ss 231 237 598 596 114 lsa it was installed by a reputable ls1/lt1 tech and tuned. Any ideas? Also when should I replace my springs? I've never had more than normal metal on magnetic plug.