Originally Posted by breno
I'd be interested to know what the head and zorst temps are in the those temperatures..
EGT actualy goes up significantly in colder weather. The cold dense air causes a leaner mixture because the molecules are much closer and more air is actualy entering the cylinder on each stroke.
In the ultralight community, they run their engines rather lean, monitored with guages, to avoid rings coking up and sticking.
Some of them have to richen their mixuire in cold weather to keep the temps below max allowed.
If your mixture is on the verge of too lean in warm weather, you could easily sieze the engine in cold weather.