Here is one more question for you guys. It is an extension of my other topic, but thought it may get more looks if I started a new one.

How much lift do you lose due to pushrod and other valvetrain delfection once the real spring is installed? When measured with a checker spring and lash set to 0 I have .649 lift. With real spring back on and lash set to 0 I have .629 lift. So I am losing .020. Is this normal due to valvetrain deflection? This is with 170 seat and 490 open pressure, crane roller lifters, crane gold roller rockers and stock GM 3/8 pushrods. I read somewhere that most GM pushrods were .080 wall unless they were on a non adjustable valvetrain engine, but I don't really know the wall thickness. And, I don't think these pushrods are chromoloy. I wonder if I need to step up to some better chromoly pushrods? An are 3/8 pushrods sufficient?

Chad - Your .020" deflection is about right for the spring pressures (which appear a little light to me for a .649" lift) that you're running. FWIW, we just mocked up a new motor last week and, with considerably more lift and spring pressure and with 1/2" x .120" wall pushrods, we had a little over .040" deflection. Regardless, we have run 3/8" x .080" wall pushrods with 800# springs in the past (although I would probably use 7/16" pushrods on the same combination in the future).