Carbs are cooled by 2 actions.
The pressure drop as air passes through the venturi can be up to 25mmHG, enough to cool the carb by 8-10C
The evaporative effect of petrol as it is sprayed out of the jet, which can cool the carb by another 10C.
Even at quite warm temperatures it is possible to create carb icing, supercold water which then sticks to the butterfly and throat, forms crystals and can actually stop the operation of the carb.
You can see this happen if you take the core out of the tyre valve and watch the ice form as the air rushes out. If you do the same thing by holding the valve down, sometimes the ice will plug the valve and the air will stop until the ice melts.
The engine though gets warm and can heat up the carb. The temperature will depend on the ambient temperature and humidity, the heat transfer from the engine and the driving style.
But in general, it is normal for the carb to be cool to the touch, but if the heat transfer from the engine is effective, the carb heats up again in parc ferme.
|
|