Cam ground pistons
 

I know current production pistons are cam ground to compesate for heat distortion. Were they always cam ground or originally true round ground? If so, when did that occur?

Re: Cam ground pistons
 

they were always cam ground

Re: Cam ground pistons
 

Not all manufacturers used cam ground pistons. It wasn't until the advent of aluminum in piston manufacture that cam grinding became routine. In Cushman engines the cam ground pistons didn't appear until the early 50's. Of course these were air cooled engines and had more radical temperature variations than a liquid cooled automotive engine.

Re: Cam ground pistons
 

Many manufactures used split skirt pistons,Ford used them on the Model A.Phil

Re: Cam ground pistons
 

I have a Van Norman piston grinder which I'm sure is from the 1940's, that will grind them either way. I think that is the time frame (40's) when it became common.