Carb Heat; add before or after power reduction?

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Darwin60

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Darwin60
C-182 O-470U on downwind would it be better to add carb heat and then reduce power or reduce power and then add carb heat. Seems to me the former would cause the engine to stumble for a shorter period of time if carb ice was present from the descent to pattern altitude.
 
Before. Carb heat is a heat transfer function. If you pull power, you are reducing the heat source before it has a chance to transfer.
 
Before if you want it to work well...more heat available with more power.
 
Remember, carb heat comes from exhaust heat
 
Before, for all the above, and also because the 182 with an O-470 is a terrific ice maker!
 
Interesting answers. Personally, if we're talking about the standard prelanding combination where one follows the other in a second or two, I don't really see where it makes a difference.

More fun question is, do you close carb heat bofore or after landing?
 
midlifeflyer said:
More fun question is, do you close carb heat bofore or after landing?
Click to expand...

I do it after. I can see the benefits of doing it before due to the fact that it leaves open the alternate (and unfiltered) air source, but I just don't worry about it until after I'm on the ground in order to simplify my task load on short final. When I have been flying a lot lately and am not rusty, I will close it after touchdown when I lift the flaps. Otherwise, I wait until I stop when I get off the active runway and do my post landing check list.
 
Carb gauge, keep it the green. and not worry :)
 
Doing it after reducing power might also result in forgetting it altogether.
 
I suppose that the decision-making might be more complicated if landing on a dirt field.

PPC1052 said:
I do it after. I can see the benefits of doing it before due to the fact that it leaves open the alternate (and unfiltered) air source, but I just don't worry about it until after I'm on the ground in order to simplify my task load on short final. When I have been flying a lot lately and am not rusty, I will close it after touchdown when I lift the flaps. Otherwise, I wait until I stop when I get off the active runway and do my post landing check list.
Click to expand...
 
Dan Thomas said:
Doing it after reducing power might also result in forgetting it altogether.
Click to expand...
Maybe. But doing it after for most means immediately after. There is a potential operative advantage in that it associates seeing a power reduction with adding carb heat, whether the power reduction is due to us or not, like what happens with carb ice. We see the power reduced by itself and it results in, "I need to reduce carb heat."
 
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