I was having trouble getting my Magnum to run consistantly so I looked into it further and found a leak on the intake manifold from when I adjusted the valves so I resealed it and tuned the engine again. Now it runs very smooth with a solid idle at 3100rpm but it was peaking at an amazing 11800rpm with a Master Airscrew 13"x8" K series prop! Looks like I need a bigger prop.
Note: Tach was a TNC