Carburetor heat slight miss or roughness

[Dwb62]

When applying carb heat for landing I feel a slight miss in engine smoothness, is this normal or is this a problem that should be looked into. 

[hammdo]

If mixture is also full rich you’ll feel a slight ‘bumble’ as there is too much fuel for the air mixture. On mine I don’t add carb heat unless absolutely necessary — I do have a carb temp probe though…

-Don

[DXB]

1 hour ago, Dwb62 said:

When applying carb heat for landing I feel a slight miss in engine smoothness, is this normal or is this a problem that should be looked into. 

It's fairly normal, though you don't want to get it so rich that it dies.  It's good to make idle + carb heat the last step of the runup occasionally to check for this happening.  You could enrich the idle mixture slightly if it is a concern.  Also I actually turn carb heat off after my last GUMPS once on final - one less thing to do in a go around.  It's nice to have a carb temp gauge - you'll notice that carb temp actually runs quite high most of the time while reducing power, so ice risk is very low with our setups (but not zero).

[Dwb62]

Thanks for your reply, just wanted to know if it is normal, thanks for the run up info also.

[Hank]

17 minutes ago, Dwb62 said:

Thanks for your reply, just wanted to know if it is normal, thanks for the run up info also.

I descend power on, resetting every couple thousand feet to my cruise MP and EGT numbers. So Carb Heat is not required. Power is reduced to drop Takeoff Flaps prior to pattern entry, which pretty much reduces speed to 95-100 mph.

Dropping gear and further throttle reduction starts my descent to the runway. I also land without carb heat, 18 trouble-free years and counting. 

The Carb Temp gage is nice to have, too. It allows use of partial Carb heat, just use enough to get the needle out of the orange stripe. Oddly, my Carb Temp gage is marked in °C, while my OAT is in °F.

[Dwb62]

Thanks for the information. I appreciate it.