Carb Heat RPM for RV-6 O-320?

[Bad Sheila]

Does anyone know the rpm lower limit of the green zone to use the carb heat on my O-320 D2A?

Also, what do you recommend for the upper limit?

[Vern]

I've always used <2000 rpm, select carb heat.

Many RV's with the short 4" vertical tube above the airbox do not have adequate heat available. Engines have quit because of the inadequate carb heat. I had a second heater muff around my exhaust stacks on my 6A.

See NTSB reports.

[Sam Buchanan]

Originally Posted by Bad Sheila

Does anyone know the rpm lower limit of the green zone to use the carb heat on my O-320 D2A?

Also, what do you recommend for the upper limit?

I never use carb heat unless I suspect ice (has happened once in the air, twice on the ground........O-320, RV-6....twelve years, 1015 hrs). The Warrior I flew pre-RV used the same engine and induction system and carb heat was not part of routine ops in that plane. I do check it during every preflight runup, however.

[penguin]

There's no problem with using carb heat at any rpm. Like Sam I very rarely see any icing (O-320, RV-6A, 8 years, 400+ hours), and usually only on the ground (before the oil has warmed up) when the air is cool and damp. I have a 6" long heat muff on the exhaust cross tube, and a carb temp probe outputting on the engine monitor - carb temp warning has never flashed once the oil is warm.

Pete

[N941WR]

I have a carb temp probe installed and I have found that slowing down actually increases MY carb temps about 10 degrees F.

Still, the "stock" van's carb muff is next to useless so I installed one of these heater muffs from Wick's for $60.99 and it will put out some heat!