do these trucks when you start them normally have a loping idle?

[yellow400ex05]

I'm trying to figure out if my truck has an aftermarket cam in it and when i start it anytime after I start it whether is cold or hot it has a nice little lope to it, a noticeable one, I didn't put this engine together but apparently its a GM crate engine, so i think it might be cammed, but i can't be for sure. when its running and i put the clutch in after I've been driving it'll idle higher and wont have nearly as much lope to it, as if it just idles higher when you've been driving it.

anybody got a video of what these trucks normally idle like when started up? do they lope because they are carbureted?