Did the springs that you took off the engine have a flat coil damper inside? All sbc stock springs have them but from what I have seen the factory stock 6cyl springs don't. (Maybe someone who has tore down a lot of engines can confurm this) Someone could have put in sbc springs in before you got the car. I just tried to look inside the oil fill holes in both the engines that I have, can't see inside well enough. I ran the Crane 203901 cam (.530EX lift) with sbc springs and did not have problems. I foolishly did not check for coil bind and just got lucky. Truth be known it had to be dang close if not barely touching! That was when I was young and dumb. Now that I am old and dunb I'll make different mistakes. Jay
