I had them on the old Max Wedge, Isky 550 Super LeGarrea,(?) in fact they helped real good, I could rotate the spring-retainer-valve with my fingers, lol, I had run them like that a few times (6800) before new ones. Amazingly no time difference with new ones. I added a bolt to center of holder since there’s no heat crossover in max heads (the springs made it bend up). It was all on there when I got engine.