Okay, only a member a few days and already need some assistance. Good timing! Here's my problem: After a recent auto cross, my 1974 350 small block has developed what sounds like an ignition miss along with a metallic ticking sound. The engine runs as if one cylinder isn't firing. However, the plugs are all clean and get great spark. The timing is correct. There are no faulty vacuum lines. The plug wire have no signs of crack, burns, etc. No plug is cracked. For all intents and purposes, I cannot find any fault with the ignition system. The metallic ticking is somewhat difficult to pin down. I've narrowed it to the upper portion of the engine, but can't seem to get any more specific. Even a stethescope isn't helping me locate it. The ticking seems to come from everywhere. The sound is kinda like a cross between a metal rod tapping the valve cover and an intermittant vacuum leak. It varies with the rpm of the engine. I'm almost certain it's mechanical in nature. I've been told locally that a broken valve spring couild cause the symptoms I'm experiencing. I've also thought a failing hydraulic lifter could also be the case. Valve springs I can readily check, but how does one check the lifters without tearing dowm the engine? My service manual is rather lacking in such details. Any other thoughts? I'm going into driving withdrawals. Please help!