I called them yesterday and they said that the 77 motor home 8:1 compression 452 head 440 I have is the motor they designed the cam for They said I can use stock springs and everything else. I'll be ordering their lifters too. I just wanted a good running 440 in this car not not a monster horsepower motor so if the whiplash cam makes it sound good that's a bonus. I should be ordering it today.