how long do valve springs last? should they ever be replaced on this car? i have my head off and the vavle springs off so that isn't an issue

millage on them = 80k
year 00

 

If you're changing cams then you must replace the springs. If you're staying stock then I would reuse them unless you've been having problems with the valve train.

 

I'm curious as to why this is done

 

some cams change how far the valves are pushed open...if the springs aren't strong enough to handle the new lift you may have what is called "valve float"...that means the valve will hit the piston and the valve stem will bend...

 

Thanks for the clarification!