Idle RPM?

I have an RV-9A with a Lycoming O-320-A2A and a Cato three blade propeller.

If I attempt to get the idle below about 850 RPM, the engine will stumble.

Is this normal? I?m wondering if the light weight propeller is not providing any fly wheel effect, or do I have a carburetor problem?

Does anyone have the same engine propeller set-up that idles smoothly at low RPM?

Thanks,

Tom
2019 paid dues

I have a 0-320-D2A and 2-blade Catto, dual slick mags. When warm I can get a smooth idle down around 700 rpm or so while on the ground, but that is still way too fast for landing unless I want to glide forever. (See multiple threads in the archives about the problems too high of an idle creates for landing a -9/9A). Thus, I have my idle set to about 550 or so and just use a little bit of throttle during ground ops to smooth it out.

Beyond the above, I can't answer whether you might have something else going on. Good luck though.

I have a 9A with an 0-320-H2AD and Catto 3 blade, but with EFII. It will idle down to 500 rpm easily. I usually idle at 700. I think you have a carb problem, or an induction leak. May be an idle mixture issue.

Thanks. I’m inclined to agree with you.

I have a IO-320 with dual P-mags and a three blade Catto.
My idle is set to about 550 but as Steve says that is for better landings. It is a rough there and is close to dying so I keep it bumped up to about 700-800 while on the ground.
When you say "stumbles" are you saying it stumbles when applying throttle from idle or it is just rough? I would assume either way it is mixture/carb related.

Both. After landing it does not want to accelerate. Below 850 the idle is rough and shakes the airframe. I have the bottom idle about 675 for landings.

I have p mag right. Standard mag left.