ORIGINAL: Mustang Fever
The engines are cooling ok. I was just not letting them cool off at idle before shutdown after a WOT run.
As far as cylinder head temp, I don't know what's best. I ran them up this time about 1200 rpm off peak, and they're holding at 275F with 88F ambient temp. They use a lot of gas at that setting, though, and rapidly drop below 200 at idle.
I've read one place that says don't go over 350F head temp, and at least one other that says 225. Anyone have any ideas?
honestly that prop is too big for the ax55 when its breaking in, i would use a 11x5 or 12x4 (both apc), you want your engine turning about 13500 on the ground, this will help with your cooling problem a lot and it will give you more power.
my temp reading is very simply, put a wad of spit on your finger and rub the drops over the cylinder head, if they sizzle off imediately your to hot. if they sizzle off after 5+ seconds your fine.
if it does sizzle off instantly your prop is to big or your cowling is messed up.