I have heard from another person on here that each pitch is worth 200 rpm. Most motors, from what I have read, need to turn between 4500 and 5500 rpm wide open throttle. I don't know where your rpm's are, but it sounds like you are not too far off in terms of getting it on plane so I would think a couple inches would be plenty. What diameter prop are you running? You can get a steeper pitch with a smaller diameter or a smaller pitch with larget diameter. I think it is rocket science somewhat! lol