Is it a bad idea to replace one haeds valve springs instead of both the thing is i am taking off my cylinder head and while i am taking that off i would like to replace the valve springs would it hurt the car if its just one side. and also since i am taking my intake manafold off the car should i get it ported or not?

 

You can do a "heads-on" valve spring replacement on the other side. That would be the best option, to have new springs on both sides.

Crane makes a SBC heads-on valve spring compressor that works well on the 4th Gen F-Body’s where the cowling hangs over the back two cylinders on both sides.

WD

 

Not going to see any gains on a ported intake without porting the heads or upgrading the cam.