Material used for forged steel rocker arms?

[pheyden]

I have a project to reproduce rocker arms from early Fiat 4 cylinder OHV motors.

The ratio is 1.45:1, and the rocker will be fitted with a bronze bushing where it rides on the shaft. I have heard that EN8 (SAE 1049) or EN19 (SAE4140) could be used. In either case I would like to have the rocker body to have some ductility with the adjuster end and wear pad hardened for increased wear resistance.

Are there any other options?

Paul

 

[TVP]

EN19/4140 sounds like a good option to me. The whole part could be quenched and tempered to achieve a reasonable balance of strength and ductility, while the adjuster end and wear pad areas could be locally hardened by induction or flame in order to achieve a higher hardness surface zone. Q&T would probably be in the 32-39 HRC range, with surface hardness ~ 55-60 HRC after induction or flame heating.

 

[CoryPad]

There are many options, but likely you are limited by quantities. Are you making 10, 1000, 1 million? If it is either of the first two, then TVP gave you excellent advice. If it is the latter, then there are several other choices available.