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Carb Throttle Arm and Cable Bushing…

Piper J3

Well Known Member
We are doing Dynamic Prop Balance on RV-12 with 370TT. IPS started at 4.6 and now at 0.6 without too much fuss. We are also doing carb balance and notice throttle arm / cable bushing wear on both carbs. See photos below - throttle arm photo is out of focus, but you can still see elongated hole…
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Hey Jim,

Be sitting down when you price those parts. :eek:

But, as I recall, you have a couple of spare used carbs. The parts on those may be OK to use?
 
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Right you are Tony - see pic below. I bought two (never used) 914 carbs on eBay a couple years ago for $395.
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I had wear on mine at the full open stop, there was a notch where it hits. The cost scared me so I welded it with the TIG. I would probably do the same if mine wore like yours.
 
Right you are Tony - see pic below. I bought two (never used) 914 carbs on eBay a couple years ago for $395.
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Those look great.
You will need to replace the Nylock lock nuts (and metric screws) with all metal U.S. lock nuts if you want to stay in compliance with notification 14-07-03.
 
Those look great.
You will need to replace the Nylock lock nuts (and metric screws) with all metal U.S. lock nuts if you want to stay in compliance with notification 14-07-03.

Looks like we saved ~$160 + shipping. Why so expensive???
 
Jim,

I am based at I19 and would like to have my prop dynamically balanced. Did you hire someone locally to do the balancing? Did you take any pictures of the process?

Thanks
 
If you flew for a lot of hours at 4.6 ips that could be some explanation for the wear.

Rotax recommends this pivot joint be lubricated occasionally. A recommended method is to use a drop of engine oil from the dip stick on each point during each oil change , then wipe off the excess with a rag after it soaks in a bit.
 
Correct answer would be Rotax should make parts from hardened steel. $48 for arm and $28 for the bushing per carb. Nice business, if you can get it...
 
We are doing Dynamic Prop Balance on RV-12 with 370TT. IPS started at 4.6 and now at 0.6 without too much fuss.
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I have a Smart Avionics balancer that I use for dynamic balancing and the instructions state that if the initial dynamic balance is greater than 1.5ips, the propeller should be removed and static balanced, or locate and correct a mechanical issue (think carb balance, prop track or other issues) before proceeding with the dynamic balance. If the initial balance was actually 4.6ips and you succeed in obtaining a semi acceptable balance at a given rpm, you will still have balance issues at varying rpms due to inertia associated with ips theory. I have a Prince wood/carbon fiber propeller on my RV12 and balanced to .02ips in flight at cruise rpm. However, I have no carb sync to deal with.
 
Oooops, I misspoke, IPS started at 0.46 and not 4.6. Final balance is 0.06 IPS. Good thing I don't balance the checking account...
 
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