Bax,

I have an one year old 46ax, broken in correctly, runs great. Recently, I've been playing around with props to pull my US 40 around. I've ended up really impressed with the 12x4 apc performance. By the way - I'm at sea level, 15% nitro, Tower muffler and tached a peak 14,800 with the 12x4. My concern - from the 14,800 peak, I richened five clicks for flight, but the engine runs hot to touch. My first care is for the engine's longevity. So, is this too much prop, and should I switch to a 11x4 or 11x5, or richen the 12x4 more for cooler runs? And if richening for cooler runs is an option with the 12x4, at what point is too rich to where I'm caring for the engine, but mitigating the 12x4 performance? Appreciate any advice ...

If your engine is running rich of peak RPM, it's just fine. It's normal for it to get hot enough to cause severe burns. As long as it's set to be rich of peak, and is running well, don't worry about its temperature. We never check temps on engines we run.