I am changing from 350 to 455 on my 1972 Cutlass S. Do I need to change front coil springs too because of added weight? Thanks for the help.

 

I have never done this swap but my understanding is there is about 100 pounds difference in the 2 engines. From what I have read, most people don't change the springs. Of course if the springs are original it might not be a bad idea.

 

I have done this swap without changing springs. If you want to get a feel for the difference in ride height, sit on the front fender. You'll note that there is little difference and in most cases these cars at too high in front anyway.

 

my experience with coil springs are with motocross on 4 wheelers, but other than it wanting to sit a little lower it may also want to bottom out when you hit i dip in the road. a coil spring will have a differant spring rate for larger weight. if it sits lower it will want to got through the remaining travel faster because there is less of it and also because it has a lower spring rate than it should. i am sure you would be fine but i am also sure that it will want to bottom out in a dip. if you don't change them just be aware of this fact for a while till you know how it will respond to the road.