Medallion .15 NVA nipple size

Hi Bob,
Your numbers help tremendously. Since I have both of the other other engines, all I need to do is compare the .15 to them to see (hopefully) a difference between the biggun and littler ones.

Now to figure out why this engine ran only when the needle was about to fall out of the spraybar!

Jim, is the front collet ( carb body ring) tight? If the plastic body is leaking air, this could constitute the need to open the needle as far as you did to get it to draw fuel. The other would be that the needle is incorrect or not fitting the spraybar properly. Place oil on the threads and hold your finger over the venturi while turning it over. Watch to see if the oil gets sucked or blown off. The other issue is that seeing these spraybars are brass, they get a case of the green death inside of them. That thick gooey green mess which can cause enough blockage which doesn't break down immediately with no fuel. Really give it a work out with a piece of wire through it and in the center hole.

Thanks Ken,

All good points. This engine was bought used, and looks to be used very little. The glow plugs kit bright, and smelled clean...no fuel residue burning off.

My mistake was taking an unknown engine and slapping it on a plane. I usually run an engine on the stand before using it. That has stopped building planes around worm out engines several times in the last few years.

My "fuel system" is also an unknown...some balsa with a fuel pipe and epoxy with a latex finger for a non-pressure bladder. This was a first for me. All my other models get hard tanks.

Once I determine the correct NVA is in it, then I will remove/clean the NVA. Then it will get benchrun, tached, and re-installed. I really want to see this engine fly on that plane once!

The one time it ran, I was shocked by the slower speed and bark it had compared to an .049! It just sounded awesome!