Originally Posted by
mk13
Hi!
I am one of the French people to whom Bert sent a conversion kit a few days ago.
Thanks again Bert the kit and your kindness!
This is the first time I do this mod and the first time I run a glow engine 😅
I did the mod on an old training plane (Taramis) with an old OS max 25RC engine.
I put Billy603's (Guillaume) setting for the curve. The engine runs, but I have a bubble problem between the valve and the carb. I don't understand how these bubbles can appear in this hose because I don't have bubbles before the valve (between the tank and the valve). Do you think it is possible that there is an air leak between the valve and its support?
I will try to put a video of the first run.
I have seen extremely fine bubbles (almost like a dust or mist) that are no problem. They are usually caused by vibrations (like a form of cavitation). These very seldom cause issues.
If however the bubbles are large enough for them to be visibly round in shape, and are stagnant in the line when you hold the nose down (the bubbles stay in the line and do not flow with the fuel), it is probably heat (valve housing touching the engine) or very hard vibration (the housing swinging to and fro and hitting something). Best is to relocate the solenoid to a place with less vibration. Although in general, te closer to the carb, the better, the position of the solenoid is not very critical and up to 10 cm distance I have used succesfully.
Since you have a very small engine, it can be of help to select a smaller diameter fuel tubing between valve and carb nipple. This helps maintaining a bit of "velocity" in the fuel line, and this helps with carrying away any bubbles. The smallest size availlable is 1,8 mm inner diameter. It is a bit hard to get that on the connections, but it can be done when the tubing is carefully heated a bit (for example a hot air blower or hot water).
Mind you, most likely it is necessary to fine tune the curve you took from Billy. It usually is a good starting point, but it is extremely rare that an existing curve 100% suits a different engine, EVEN if the two engines are identical.
Looking forward to a video.