484 purple cam..JUNK

Did you degree it when installed? In a 340, they like to be installed at 102ish.

I'd crank as much initial timing into it as the starter will handle and see where you end up. It may want 28*. I have a tight lashed 284/528 mechanical in a stock compression 70 340, liked 24* initial and will idle real easy at 800 rpm.