Ed

My BGX-1 is now mounted in an aircraft, and almost ready to fly. Will OS-F plugs insure greater reliability ? The engine is semi inverted, with the cylinder angeling down 45 degrees, and the muffler exiting at the bottom of the aircraft. It has been running beautifully on my test stand using only medium diameter fuel tubing, and I'm not sure if large diameter fuel tubing will be required. The inside I.D. of the Carb fuel nipple, and tank piping, seems to be about the same inside I.D. diameter as the medium fuel tubing. Do you think that large diameter fuel tubing is a "Must", and is it better to use the OS-F plug ?

I'm looking for maximum reliability in a very expensive warbird. Is the BGX a good reliable engine for this ?Thank you all.

Ed


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Bax

My Feedback: (11)

While medium-size fuel tubing is OK on a test stand, it is definitely no good once you've mounted the engine in the airplane. That's because the engine on the test stand never changes acceleration or attitude.

We go to large-size fuel tank, re-plumb the fuel tank with large-size copper (or brass) tubing, drill the clunk to a larger diameter and go from there. Because the metal tubing and the silicone tubing are not quite a match, we have to wire-tie everything in place. The only fuel tanks that will allow you to do a good job of enlarging the fuel tubing sizes are the Sullivan tanks. That's because they have the rubber "cork" that seals around the metal tubing. Other types of tanks with the molded vents and such won't do the job. We wind up drilling-out the nylon compression pieces that go on either end of the rubber "cork". The clunk is drilled so that it has a constant large inside diameter...it normally comes with a large diameter at one end and a small one at the other.

Once the mods are made, the engine will run very well as long as you make sure you have good muffler pressure. Yes, you do have to drill the muffler tap so that you can use large tubing there, too.

Ignore the inside diameter of the fuel nipple on the carb. That's because it's "right there". You want the large-diameter tubing up to the carb because "regular" size tubing has significant fuel-line drag, which will cause the engine to run lean.

Run the engine with fuel that has 5%-10% nitro and use an O.S. #8 glow plug. If the type F works, then use it.

Ed

Thanks Bax, It will be large fuel line, and large brass tubing, from the clunk all the way to the Carb nipple. ( Including the bored out clunk )

One remaining question however. Do the vent and filler tubes, and lines also have to be large diameter ? ? ?

Thanks for all of your help here.

Ed