Edelbrock Victor small block head……

I had a machine shop look at the heads and even replace all the valves too because the 318 I had them on before broke a valve and had bent most of the others too(poor clearance in the bore). Like I mentioned before, the engine was still on its break-in period so high revving was off the table, at that point there's no way I could've floated the valves. It could've been a preload issue but I did cylinder 5 with the same preload as all the rest, why would this one let loose?
Potentially they’re all on a similar path, and this was just the first to indicate the issue? I wish I had a better answer for you. Hoping all the best for you and that you find a quick and hopefully not too expensive resolution!!!