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?