Builders.
Those were the conditions, and I let the test engine idle with no carb heat for 5 minutes at 850 rpm. We were testing the Stromberg the builder is going to use on this engine. Look at the white patch of ice on the manifold. …… and no, this isn’t a Corvair thing, Continentals are prone to this also, and if your going to be a real airman, you need to have a good understanding of the physics here.
WWJR
Out here in the desert, at Palm Springs, (right now, it’s 85 F and 10% humidity, dew point 24 F, in January, no less), we can get lax about carb heat on low power settings because the humidity is so low and carb icing so infrequent, but if one flies over to a coastal airport, a little over 100 nm away, with its usual humidity, it’s much easier to get carb ice. Best practice calls for putting on carb heat every time. It’s a habit that can prevent loss of power in non-desert conditions.