My 71 ss454 is making a noise that a friend says sounds like a broken valve spring. What are the causes and signs and smyptoms?

One of the symptoms is a loud tapping from the rocker arm. You will have a miss usually on 2 cylinders, one on each bank that share an intake runner. The easiest thing to do is take off the valve covers and inspect the springs. If you can rotate one with your hand it is bad.

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Philip Valentine
Gold Member #42
"Perseverance is not a long race; it is many short races one after another."
philip@chevelles.com

David,
Pull the valve cover, look for anything obvious (broken pieces), pull the coil wire or unplug the HEI depending on which type of ignition you're running, have a friend bump the motor over, on each cyl, make sure they all are opening about the same (a wiped lobe won't open as much or at all), after the intake valve closes, check the rocker arms for loose (loose nut/broken rocker/bent push rod), see if the valve spring can be rotated (it shouldn't), try to rotate the push rods (they should spin true), this should put you on track.