The engine does have what sounds like an exhaust leak but there isn't an exhaust leak. It is a clattering noise. I have added lead mixture to the gas ever since I bought the car to prevent valve clatter. Can't figure out where the noise is coming from? The car is mostly original except for the power disc brake conversion and I had it completely re-wired. I did not know if I could convert the old point system to an electronic ignition system or if it would just be better to think about putting a new crate engine and tranny in. I am not a mechanic and haven't worked on old cars since 66 when I had a 52 Chevy in high school. Now that I am retired, I wanted a everyday driver with modern electrical and dependable engine/transmission.