my boat does not know its a 2006 but my bank book does

who's to say the dealer even knew when it was built ? could have come from GM's warehouse a few years old...not uncommon..your receipt is your new as of date..

Sorry, this is not an urban legend. I did read in one of Bob Teague's tech articles the same as tinman has described. Bob Teague could be described as a "suburban legend".
(He is from the city)

Well, if you read it in a magazine, it must be true.

You guys had better start backing off your rockers for winter storage... Because if you've gotta replace your valve springs at some point, becuse they sat too long in one position... You may wind up getting a set that's been sitting on the shelf for a couple years... Then what??

I own a transmission shop and I have bought many parts from the dealer that are dated 5, 6 even 10 years ago, same way with snowmobile replacement parts. I am under the understanding that gm quit casting the gen 6 502/454 blocks some time ago so it wouldn't surprise me that it is dated 06, just run it, Smitty

Lets go with your theory...so if YOU wrote it on here it must be true ? lol. Many reputable engine builders have said/written articles about this. I guess they all must be wrong. A spring is basically a wound wire with a certain tensile strength. Due to the constant load/unload (and a few other factors), they wear out (loose seat pressure). The same thing happens when you compress a spring and hold it in that position (loaded) for long periods of time. I'm not talking weeks....I'm saying a considerable amount of time. Everytime you fire that motor...you are essentially weakening that spring. Then you say its ok to compress it for a long period of time ? You probably dont unload (back off) your expensive torque wrench when your done with it either huh ?
Lastly, the springs sitting on the self are in a neutral state...as in unloaded...not compressed...not squeezed...get it ? You better do some real research sir.

Actually, my "real" reserach has been done... on a daily basis over the last 28 years... in my shop, with my Rimac valve spring tester, during the course of building and rebuilding hundreds and hundreds of engines... thus the basis for my statements. You see, unlike yours, my research dosen't consist of reading magazine articles by other engine builders. Thanks for the schooling on valve springs though...

And yeah, I get the part about new valve springs sitting on the shelf being "not squeezed". My reference was to the mindset here that parts, valve springs or otherwise, that have been sitting on the shelf for any period of time are somehow no good... get it?

I'll leave you guys alone now, so as to not get any further off track here...

Oh..I get it alright. I respect your research on real motors over the years. I myself have changed a valve spring or two. You see...I own and race a '65 GTO that makes 1400hp. Its also STREET DRIVEN. So, I'm well aware of the lifespan of valve springs. I've also built dozens and dozens of stock...to wicked fast motors. What I'm getting at is....your not talking to some retard thats never turned a wrench. I'm smart enough to know that I'm not Grumpy Jenkins...but I'm also confident in my abilities because of the research and experiences I've had over the years. The original poster stated that the motor was brand new. Lets say that he did find an original...never been fired motor from '06. My point was that if its been sitting on the shelf...untouched for 5 years, then I'd be suspicious of some of the internals. And yes...you are definately correct about some parts sitting on shelves for years with no problem. Compressed valve springs are not one of them.
So...whats the name of your shop ? Or your name ? Wheres it located ? You might drum up some business.

I can say I know of Cubic Inches and he is the real deal, I wouldn't question that.

A compressed spring, left compressed for years will lose some of it's pressure. It may not be enough to amount to anything noticeable but it will absolutely happen. It is physics, opinions don't matter.