RV-9 owners of IO 320-mixture arm rubbing

[ron sterba]

On my new IO320 it came with a Precision Airmotive servo. The curved mixture arm was right against lower cowling even without bolt installed. Sent for straight arm and installed it with the rod end bearing with AN3 bolt but only have .290" clearance between AN3 bolt head and cowling. Its my understanding that the engine shakes at start up and shut down and will wear cowling but most of all the mixture arm shouldn't be rubbing at ALL! What did you do to elevate the rubbing? I was thinking of a clevis on the arm.

Ron in Oregon QBRV9A

[Dan B]

You will need more clearance than you have for all the movement the engine will do in the mounts for torque and vibration. I had to cut out the cowl in this area and fabricate a blister for clearance.

[Norman CYYJ]

I had this problem on one plane that I built. I took the arm off which is made of steel and heated it up and reshaped it. Lots of clearance when modified.

[ron sterba]

Dan, This is what I thought of was a blister type bubble but I thought it was a shame to change the slim line of the cowling. Thanks
Ron in Oregon

[ron sterba]

Hi Norman, I to thought on this reshaping of the arm. The other possibility is talking to the manufacturer about maybe the throw to FULL RICH on the TOP swing of the arm instead of the bottom. This would getting rid of the INDENT plate to the airbox. I hope more posts will come as more builders are going to Fuel Injected engines. Maybe there is a horizontal Fuel injection servo with levers that would not have any problems with interferences Dontno. HATE to cut the cowl!

Ron in Oregon

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[MS19087]

Check out my photos of this area on www.n91rv.com

[ron sterba]

Thanks Mark, Did you get your servo from Precision airmotive Inc. out of Marysville Washington? Nice fiberglass bubble job! Another idea that's very workable. Thanks Ron in Oregon

[MS19087]

Is what I am running on my io320.

[rv9av8tr]

I would suggest sending your servo back to Precision and have them reset it up for upward swing.. While it does solve the cowl interference, it also makes the control shaft alignment "tricky" as you can see from my setup. I've not had any issues with this.

https://picasaweb.google.com/1166542...27312893739666

[kbehrent]

Do you have a 320 lower cowl or 360? There were issues with clearance for IO-320 when using the 320 lower cowl so Van's recommended the 360 lower cowl for me and I have no clearance issue.