OS-46 AX Engine Dies When Airplane is Nose Down

by Dave
(Pittsburg , Ca)

Hello, I have an OS-46 ax mounted in a world models skyraider. It runs fine nose up , upside down , sideways and level flight but as soon as I point the nose down it dies instantly.

When I say nose down I mean nose down even just a few degrees . If it running straight and level and you lift the back of the plane 2 inches it dies instantly. It doesnt raise in rpm nor does it spit and sputter, it just stops.

I am confident my tuning is ok. I have tried the pinch test with mixed rtesults. A couple of times the rpm's raised a little after pinching and a couple of times pinching seemed to have no effect. I pinch it for about 2 seconds then let go.

I have read about how it may be the clunk being to far back causing that problem but that is not the case. Also I read posts where they say the plane is suppose to die when its nose down and not flying because it runs out of fuel but when its flying the g forces keep the fuel around the clunk.

That may be true but I have been flying for 20 years and have never had a plane that I couldnt tilt forward when I am ground checking the motor. Plus if my plane was running out of fuel wouldnt it take at least 2 or 3 seconds before it used all the fuel in the lines?

My plane dies instantly , the second the nose points down at all. However this only seems to be the case at full throttle. At 1/2 trottle it continues to run.

Got me baffeled. Any ideas??

Thanks Dave