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Old 07-12-2011, 08:44 PM
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Red Baron Mike
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Old 07-13-2011, 01:25 AM
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The problem is that they have a fixed airbleed built into the carb. Some have a drilled hole while others have an altered inlet (just below the screen).
With a bit of JB-weld you can alter this by going towards a circular hole and thereby enrichen the low end. Best solution is to make an adjustable airbleed like AndyW has shown how to do.

If you don't want to alter the carb you can play around with different fuels or the compression setting. Another thing is the tank height and or muffler pressure.
The only real solution though is to make an adjustable airbleed.
Old 07-13-2011, 09:03 AM
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Old 07-13-2011, 09:26 AM
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RBM

Are you running muffler pressure and is the tank pressurizing and holding pressure? I've found the high end setting to be fairly broad, so you might try a richer high end as long as you're maintaining RPMs. Since the entire carb barrel moves in to lean the mixture as it is turned clockwise (looking from the needle side), this will richen the low end setting and maybe reduce cutting out. Lastly, many of the later engines took quite a while to break-in completely, so additional running may be needed before you can maintain a 6500 RPM idle.

25% oil is a pretty hefty slug of lubricant. I generally run 22.5% nitro and 21.25% oil, but my oil is a 20/80 syn/cas blend and seems to run pretty well.

andrew
Old 07-13-2011, 11:13 AM
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Old 07-13-2011, 01:15 PM
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Couple of thoughts:
[ul][*] As Andrew pointed out, Norvels benefit from extended break-ins (not as bad as Enyas, but...). With only 6 ounces burned so far, I'd wait until you've run at least 1 - 2 quarts before getting too finicky about the idle. [*] Nitro generally improves idling and 25% nitro is fine IMO. Some folks run even higher %'s on Norvels...[*] 25% is on the higher side for oil. Dropping it to 20% may help but I wouldn't stress about it either.[*] My Norvels idle at around 5,000, and a quick google of Norvel .061 idle shows that a lot of folks idle between 5000 - 6500, so you're actually in pretty good shape.
[/ul]

FWIW, I'd just rev it up and fly the snot out of the thing for a few weeks. Good for the soul, mind, and engine.

EG
Old 07-13-2011, 01:27 PM
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Old 07-13-2011, 06:25 PM
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Mike -

A 6x3 is the absolute maximum prop for that engine. The NORVELs are really designed to turn up - you might consider a 5.5x3 or even a 5x3. That will give you a better top end and even with a 6500 idle, your plane shouldn't be moving. Until your engine is broken in well, you need to keep the temp up, particularly if it had a lot of pinch at TDC. It may be that trying to idle with only a few tanks thru it, it's cooling down and getting tight, hence the rattle.

Unlike a lot of other engines, these need to reach operating temperature quickly and stay there. Like EG said, it will likely take "several" tanks at a rich 2 cycle before it begins to come in.

andrew
Old 07-13-2011, 08:54 PM
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Old 07-14-2011, 01:15 AM
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Mr. Cox:

Thank you for the reply. I understand installing an air-bleed device would fix an overly rich idle, but my situation is the engine is leaning out during idle and running out of fuel. Per my thinking, the air-bleed would have no effect on a ''lean'' idle. What do you think?
You already have an air-bleed "device" on your engine and it is too lean, that is the problem.
You might not have a drilled air-bleed hole that you can easily see (older version have that though) but below the intake screen you will find that there is an alteration to the intake that effectively works as a fixed airbleed. The reshaped intake can easily be undone with some JB-weld and you'll get a richer low end.

I'm currently away from home, but here is an image of the .074 intake with the screen removed:

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Old 07-14-2011, 01:21 AM
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Another problem that I've had is with the split washer that is used on the screw that holds the carb in place. When the bolt is tightened the spring/split washer will still leak air.
This will mainly affect the low end and is not noticable on the high end. You can easily replace the split washer with a regular washer and enrichen the low end.
Old 07-14-2011, 08:27 AM
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