C-182 carb-heat causing rough running.

Newps wrote in message ...
R.T. wrote:

Hello all, may be some one could help me out. I purchased a 1967 C-182 K
this summer with a Continental 470.

I also have the 67 182.


When I pull out the carb the RPMs drop
considerably(200+rpm).

Yep.


I believe that it is creating a rich mixture as on a
run up I can get the rpms to come back up by leaning.

Pulling carb heat on any plane always makes the mixture rich.


I guess I'm just not
used to this kind of massive change and I'm wondering if its normal and if
there is anything I can do about it.

It's normal. I don't use carb heat because it's not needed where I
live. Don't use carb heat in the pattern just because the checklist
calls for it. Use it when you need it.

The O-470s in any Cessna I've flown had strong carb heat,
probably too strong, and we used to use partial carb heat unless the
icing risk was high. A carb icing chart is helpful so that you can use
whatever heat necessary without creating carb ice farther up in the
intake manifold as partial heat can sometimes do.

Dan

It's normal. I don't use carb heat because it's not needed where I
live. Don't use carb heat in the pattern just because the checklist
calls for it. Use it when you need it.

AOPA sez carb ice can be encountered at inlet air temps up to 104
degF. They also have a chart that they occasionally publish that
shows the tendency to generate carb ice as a function of inlet air
temp & relative humidity. This chart shows a real coffin corner at
high humidities around 50 deg F. Higher temps and there will be less
tendency of course, and at lower temps there isn't necessarily enough
moisture in the air to form ice.

That chart should be posted more widely. I can't find it just now,
but it was recently on their web site. It should be necessary
studying for us flying with carburetors.