My springs are what came on the heads originally. The cam is a stock 68 340 4 speed cam so the springs should not be an issue. Unfortunately I think the damage I find is self inflicted by me playing with the preload instead of leaving things alone. I think when I backed off and had not enough preload is when my issues started. Although I put a new set of lifters in and did a second break in, The car seems to run good but I hear almost like a pinging sound at around 2500 rpm's. Maybe I take it apart and find no issues but I have a sneaky suspicion a few lobes might have been damaged.