Originally Posted by supershaft
I was just thinking about one of my aviation bosses. He liked 1025 a lot for maybe something like this but I don't know if its available right now. There is a California pushrod maker (can't remember the brand name right now) that use to make them for the guys at B+S and whatnot with 1018. They make a lot of them out of 1018. I would prefer 1020. Personally, I like the way it machines much better than 1018! I had mine made out of 4130. It takes compression quite a bit better than 1018.
Yet another observation, not related to engines, is that bicycle frames made from 4130 chrome steel can be made nearly as light as those from aluminum tubing because the 4130 wall thickness can be reduced. The thinner walled 4130 tubing compensates for the thicker wall needed for the aluminum frame due to the increased strength of 4130.
When needing more strength, such as for a stiffer pushrod, a larger diameter tube (which may not be practical), thicker wall, or higher strength material are required. So, unless the material can be lighter and/or stronger but heavier, a weight penalty happens. No one may have yet tried the carbon fiber/aluminum composite materials - or there may be some other problems such as attachment or fatigue with the composite.
Edit: I received my 336 cam from Max BMW. It was shipped in the yellow plastic bag. It's not the prettiest cam I have ever seen and the lobes are not polished but they have a taper.