On my old heads the valve springs were only holding at 80 lbs pressure which sounds quite light. These are stock GM 71 year 920 heads. Also had one valve go bad with a worn stem plus new seals and some guide work. The Cam was a very mild Crane Blue racer which has been changed to a Energizer to match the low compression of this engine with some good lift. Should have a nasty idle now but my question is this. Will weak springs be one of the culprets in valve float. I experienced this issue with this motor and we found numerous issues when torn down. Bad rebuild didn't help with some crappy workmanship. So are valves, springs a major issue. Don't bother mentioning other heads please, this is a motor for this year only as I stated before we are building more of a project engine once I find the right core. Even have almost $500 in change saved up turned into bills already in my Z28 engine project jar. ( keep adding to it ) Thanks.