ORIGINAL: ryanofoz
Doing this at full throttle, up is fine, down shuts down the motor.
What does that tell you? Think about it.
No surprise then, it's stopping (nose down) at idle as well.
Reset the bleed air idle screw at half-way open across the small hole you can see in the front of the engine AND LEAVE IT ALONE That will be very close too the ideal setting in our climate. Temp. Av. east coast Oz MSL temp pressure and humiidity. If you must fiddle, it'll only need a minute adjustment, probably towards leaner (screw out = anti-clockwise) but no more than 1/8th of a turn at a time. If it needs more than a 1/4 of a turn either way, your problem almost certainly lies elsewhere. Ergo....
I have opened up the air bleed to a whopping 7 turns out from closed and it still acts the same. It seems unaffected by any change in the air bleed.
Refer back to my opening sentence.
Throttle response is fine from idle to WOT. If I leave it idle for long the engine will quit as well.
It's a normal characteristic of all today's Schnuerled engines with the huge ports and high timing that if you leave the engine idling for a
prolonged period, especially on the ground, and then
open the throttle too rapidly, the crankcase will be filled with such a gutful of fuel such that even with the optimum low speed needle or bleed air crew setting, they will stop. The LA is more prone to this than the AX. Partially it's a characteristic of O.S. air bleed carb. They should have asked Enya to design and make it.
With the engine inverted, this problem will be exacerbated because of where the gutful of fuel in the crankcase pools and the plug being drowned. An detrimental fuel tank to carb height relationship will exaggerate this. You can try using a hotter plug with a superior heat sink and more robust element such as an Enya #3, but that's just a kludge to address the fundamental underlying problem.
Any ideas? The only different thing is that I have the needle valve off the motor and screwed to the firewall so the needle can be turned from the bottom of the plane. I dont see how that could so it but you never know.
The height of the N/V mounting is important, as is vibration isolation from the airframe. Use good quality thick walled fuel tubing of the recommended ID & OD O.S. advise throughout the contiguous feed system. The quality and dimensions of the tubing between the needle outlet and carb inlet are particularly important to a consistant engine run in O.S. RNV type engines.
The 46LA is often beaten up on because it doesn't wear a shiny new glamour suit and afford boasting rights. In it's role, it's a superbly reliable enigne which can be flown straight out of the box. Fit a known good condition plug preferably either Enya #4 or O.S. # 8, an A3 will do if you must and an Enya #3 is fine if you're on low/no nitro , an 11x 5 APC or 10.5 x 6 Bolly Clubman prop, use fresh quality fuel preferably containing some (20% by volume of the total
oil content minimum) castor (plain bearings love it as do any engine for their first hor of running), fire her up, set her so she's in a rich two stroke at the bottom of her peak band just before she starts to significantly drop RPM and go fly. Just don't keep her at full hammer continuously during that first hour. ie: CWOT aka "Remember, you've got a throttle servo and it's not there just for ballast".
She'll run like a Swiss watch. After about 3 to 5 flights, you can start to progressivley lean her out until by about 10 (2 hrs running) you can run switch to your preferred brew, tune normal peak and go ballistic. GL.
(Edited to remove questionable language)