Tell me if this make sense. I'm using a computer program horse power simulator. Running equal components from heads, carb and cam the 429 ends up with about 50-60 hp, every time I run the figures, compared to the 460. I'm using Camquest 6 software from comp cams web site! The only thing I can think of is the smaller cylinder volume increases the compression and therebye the Horsepower. I just assumed the extra few cc of the 460, would equal extra horse power.