Here’s a tidbit from the Comp Cams website regarding breaking in valve springs. Pretty well mirrors some of the documention I’ve received from the other manufacturers. I’ll suspect that this is some of the trickle down that occurs from testing in the Nascar arena.
Breaking In a Spring
1. It is important for new springs to take a heat-set. Never abuse or run the engine at high rpm when the springs are new. Upon initial start-up, limit rpm to 1500 to 2000 until the temperature has reached operating levels. Shut off the engine and allow the springs to cool to room temperature. This usually will eliminate early breakage and prolong spring life. After the spring has been “broken-in”, it is common for it to lose a slight amount of pressure. Once this initial pressure loss occurs, the spring pressure should remain constant unless the engine is abused and the spring becomes overstressed. Then the springs must either be replaced or shimmed to the correct pressure.
And here’s the link.
http://www.cpgnation.com/forum/truth-about-valve-springs-2631.html
Lorena, Texas (South of Waco)