Technical VALVE SPRING QUESTION

I have a 390 Caddy engine rebuilt about 25 years ago. Not having been turned over yet the valve springs have been in various compressed stages. Should I just replace them all or am I being anal?

 

I've never had problems because of that.. If you want to just have fun, drive the car around for awhile and see how it does. Then fix what actually needs fixing.

 

Thanks Jim.

 

If the valve springs have taken a set, they weren't good valve springs in the first place.

 

If engine hasn't been run in yet, they are supposed to be heat cycled before hard use. At least, that's what the valve spring makers claim.

"It is important for new valve springs to take a heat-set. Never abuse or run the engine at high rpm when the valve springs are cold. Upon initial start-up, limit rpm to 1500-2000 until the temperature has reached operating levels. Shut off the engine and allow the springs to cool to room temperature. This process will help eliminate premature failure and prolong valve spring life."

 

It's fine for springs to remain compressed for extended periods of time. They do not lose tension from just remaining compressed, they lose tension from cycles. A spring that remains in a compressed condition will retain its strength.

 

Two things hurt springs (of ANY kind), hard use (fast cycling), and heat, both internal (molecule friction) heat and external (hot engine) heat. I say "two" because with one type of heat, comes the second type of heat. And usually the fast cycling..!
They can stay dormant in various stages of compression for many years without loosing more than a pound or two of force.

Mike

 

Thanks to all. Very good info. especially because I also have other rebuilt engines on stands.