From Ron Shettler, developer and manufacturer of the Quadra engine, comes a neat little trick that almost everyone can use to gain a little extra power and fuel economy from that engine.

The one problem, if it can be called that, that the Quadra has is that it does spit quite a bit of fuel back out of its carb while running. This doesn't affect the engine seriously, but if you want to make a very simple modification to your engine, you can eliminate a lot of that wasted fuel mess on your plane, and gain a little extra power to boot.

This modification involves going down to your local hardware store, and picking up a copper water pipe 90-degree elbow joint. Take your engine with you when you go, and select one that will be a snug fit inside the white plastic face on the carb.

Install the elbow inside the plastic face with silicone glue, and aim the throat of the elbow toward the front of the engine. Let cure for about a week to allow the silicone glue to thoroughly set up.

What this modification does is threefold. First, aiming the elbow mouth foward gives the carb some ram affect from the prop blast. Second, it adds a slight "tuning affect" to the carb intake to increase the breathing efficiency. Third, the extra length of the carb throat, plus the 90-degree bend, tends to trap the fuel "spit-out" and re-feed it to the engine.

Ron says if you want to carry this concept to an extreme for maximum benefit, add a tube about 3/4" in diameter to the elbow, up to seven inches long, and aim its mouth so that there is a direct ram effect from the prop blast. This will give you total tuning of the intake, and completely eliminate the fuel spit-back. In my personal use of this engine, I find this problem to be one of minor annoyance, (have to clean the model a little more), and I don't think I would ever go beyond just adding the elbow.

As an added little piece of gossip about the Quadra engine, all of the engines currently being shipped have the factory-balanced flywheel, and a new Walbro carb. Both items are part of the continuing improvement program.