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Mixture Arm

Taltruda

Taltruda

Well Known Member
Friend
Helping a friend with his condition inspection n his 8, the throttle wasn?t getting full open, the carb heat wasn?t going full cold, and the mixture isn?t t going full. We adjusted the mixture to full rich with a hair spring back on the quadrant (the mixture arm bottoms before the lever in the cockpit) but now it doesn?t allow for the mixture to go full idle cutoff. There?s not enough room to re drill on the throttle quadrant, and the current mixture arm only has the one hole. Anybody else come across this? O-360, carbureted, are there other mixture arms available?
Thanks in advance
 
I did have this same issue with my O-360 and throttle quadrant.

It took a while but eventually I got everything adjusted right and it now works fine.

If you need, drill a hole further up the quadrant lever, this will give you more movement on the cable and allow it to go full rich to idle cutoff.
 
I've also heard people suggest using a shorter arm on the carb, however where to buy said shorted arm I don't know. The shorted arm would make it so there is more travel on the mixture on the carb.
 
N941WR said:
I did have this same issue with my O-360 and throttle quadrant.

It took a while but eventually I got everything adjusted right and it now works fine.

If you need, drill a hole further up the quadrant lever, this will give you more movement on the cable and allow it to go full rich to idle cutoff.
Click to expand...

Drilling a hole further up on the quadrant would decrease the amount of throw at the engine end.
 
D Weisgerber said:
Drilling a hole further up on the quadrant would decrease the amount of throw at the engine end.
Click to expand...

Not so, it would move it in a greater (longer) arc, thus more movement.

Doing so at the carb would decrease the amount of throw. At the Carb, would want a hole closer to the pivot point to increase the throw.
 
Last edited:
Shorter arm

Thanks all, I?ll give Don a call the cable is already at the highest on the throttle quadrant..can?t get it any higher, so it?ll have to be a shorter arm at the carb!
 
Where to get one?

N941WR said:
For a carburetor? If so, putting a shorter one is way to go.
Click to expand...

That?s what I?m thinking... where to get one? Someone recommended Don at Airflow, but he?s into fuel injection.. I need a carb arm.. MA4-5 carburetor..
 
Is it really close now? Is the mixture control arm clocked so it's 90 deg to the cable, half-way thru its travel? If so, you can gain a tiny bit of throw (more throw at the carb for less control movement) by re-clocking the arm, so the 90 deg point is not in the middle of the movement. This is less than desirable, as the further from the 90 deg point you move, the more sensitive it gets to control movement. But if you're really close now, it might work.
 
If you strike out on a shorter arm for the carb, another solution may be to get a custom cable from McFarlane with more cable travel. Of course that assumes there is more ;ever travel available at the quadrant, which is what I think you said: "the mixture arm bottoms before the lever in the cockpit."

And it might be possible to cheat on the quadrant lever travel with a notch in the lever or the top plate to increase lever travel.
 
How to move the hole in the carb arm

You could press or weld a plug in the existing hole and re-drill closer to the pivot.
 
I had similar problems and got new fuel servo levers via Peter Nielson at Precision Airmotive - extremely helpful.

It was supplied with 252 1196 mixture and 252 2004 throttle levers. 252 1287 worked well for me.

Hope that helps

Chris
 
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