Rocker Arm Ratio

That ratio is the multiplier for your calculated lift. Its based off the length and geometry of the rocker. Your .509 lift cam is calculated with the stock 1.5 rockers. Your lobe height would be .339" (.509"/1.5=.339")... if you change to a 1.6 rocker your lift would be .542" (.339"x1.6=.542")

That's what I always figured it to be anyway... you would need to check for clearances for sure.

Thanks