15 OS Max III

Start with a 8X3 or 8X4 prop.

Typically the instructions would say start the engine at 3 turns open on the main needle. When its finally rinning properly it should be close to 1 or 1.5 turn open if using a muffler with pressure tap.

Since some of them shipped without a muffler.... it may run at a little over 2 turns open with no muffler pressure to aid fuel flow.

Got the throttled carb version or the CL version with just a needle valve in a venturi insert?

A 7X4 prop should be a good starting point. Set the needles so that it runs properly! Start about three turns out on both.

Throttled version.......carb....... with main needle and I believe an airbleed needle for idle??? Came with muffler OS-702 and a 8 by 4 prop attached...the engine was on a used plane he was selling ( must of ran)???

Mike R

The air bleed... you can start out with it closed. After the high en

is tuned, slowly close the throttle and open the air bleed as needed t get the slowest smooth idle possible. Depending on aging factors (ai leakage around the throttle barrel for one) it may need to stay all th way closed.

I have also seen engines with air bleed carbs that needed th adjustment screw REMOVED. For one engine, I removed the carb dissasembled, drilled the air bleed hole out 2 numbered drill size larger... then the adjusting screw was useful

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Fred...

Once the airbleed screw is fully opened to where the tip of the screw is no longer visible, that's as lean as the air adjustment's gonna get... Removing the screw will not make it any leaner. The air passes thru the hole in the carb body into the venturi. Enlarging that hole will admit more air, but total removal of the screw will have no effect, once the airbleed hole is fully exposed...

Cheers,

Bill

depends on your line of thinking... with the screw plugging th threaded hole, youhave essentially a capped "T" fitting Pull the scre all the way out and its the same as removing the cap Its not a larg difference in airflow. But I've seen it make the difference needed.

There are some who say thier OS LA .46 needed the idle air bleed scre thrown away. (and on some of them it needs to be fully closed. They'r not as predictable out of the box as some other engines...

-- fhhuber50677

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