What is the actual duration at 0.050" of mopars 340 cam? The places that I've looked into give different answers, some say it's 208* intake / 214* exhaust, while others say it's 228* intake / 235* exhaust. I have a older mopar engine builder's manual and it said that factory cams are figured by multiplying advertised duration by .777 and performance cam's by .850. I thought that the 340 cam would be considered a performance cam since it was only in the 340 and the high performance 360's. Is the .850 for the purple shaft cam's only? I'm thinking about using a cam that's equivalent to the 340 in the 318. What compression ratio would I need? Thanks everyone.