can someone explain if I have a set of PAC valve spring on a motor,how are they able to check springs at tech and determine that they are in fact PAC springs,and not factory GM crate springs ? any tech guys out there that can explain this to me ? thanks.
I haven't seen any to tell you 100% but here are a couple of things. Wire diameter, free length, surface finish, seat and open pressure.
I hear they can tell right away because the color and texture is different than GM springs. Just buy the rated GM sets and change them often.