10 sec small block
maybe a dumb question, how do you know when your springs have gone?
The only dumb question is the one you never ask.
You will start getting valve float (Springs can no longer control the valves)...
For example (and I'm no pro here but this can give you an idea)..
Lets say you normally run your car to 6500 rpm.. everything is fine...
Then sometimes it starts to pop and sputter at 6500 rpm but runs fine if you shift at 6000.
So you start shifting at 6000 rpm.
Then sometimes it starts to pop and sputter at 6000 rpm but runs fine if you shift at 5500.
See where Im going...... The springs are going away. They are losing pressure and the ability to control the valves.
Other bad things can happen too like piston valve interference.
I honestly had a chev 350 that would not rev over 3500 because the valve springs were so bad.