I am making a set of roller rockers for my car as a spare time project. Not looking to sell them or any thing so cost is not an issue I just want to do it right. My question is what my material of choice should be for the shafts. I was looking at some of the rocker manufactures websites and noticed either 4340 or 8620 steel was used. What is the difference between these two steels.
I know 4340 can be threw hardend and 8620 is case hardened. What will be better as far as stregth/wear. The shafts will have needle bearings riding on them.
I also heard H13 tool steel is suppose to have a high shear strength at high operating temps. I am not sure of the cost on this stuff but it could be a option as well. Thanks for the help.