ICO RPMs

macrafic · #1 10-10-2017, 05:16 PM

First flight with an RV-7A, 3-blade Catto fixed pitch prop and IO-360-M engine with dual pMags. Getting 730 RPM ICO on the ground and 810 RPM ICO in the air (on landing). Seems a bit high to me, but I am not really that knowledgeable.

Can those of you with a similar setup share your ICO RPMs with me? Am I in the ballpark? High?

penguin · #2 10-11-2017, 02:49 PM

Are you mixing up terms? ICO usually means Idle Cut Off and refers to the mixture control pulled fully out.

Do you mean with the throttle closed?

First of all, if you have a new engine the idle speed will change over the first few hours. 650rpm might be desirable at idle, but with a light weight wood prop you may have to accept a slightly higher idle to keep the engine running at all smoothly. Idle when you are just about to land is a factor of the prop and your ground idle speed. Perhaps stick with what you have for the first few hours, always assuming you have a long enough runway to operate from.

Pete

Raymo · #3 10-11-2017, 02:59 PM

RV-7A, Catto 3 blade with 20 lb crush plate, single P-Mag and one Slick with AFP FI. I see about the same numbers; maybe slightly higher at idle with mixture just rich enough to keep the engine running when taxiing.

Robert Anglin · #4 10-12-2017, 07:23 AM

As has been said above a light wood prop does need a little more RPM at idle set to be smooth and stay running better. A nice heavy metal prop is kind of like a fly-wheel and can stay smooth with more mass at a lower idle set point.
We run a light 12-13 pound Prince and set our ideal at around 820-850 RPM's.
I even run it a little above that on the ramp to keep the plugs cleaner a little longer. I think you are OK here with this, but it is you that have to be comfortable with you settings. Hope this helps, Yours, R.E.A. III # 80888