A friend of mine gave me a Ryobi weedwacker engine that he had converted several years ago for model airplane use, but never did. It has a Walbro carburetor (WT312) that has two brass tubes coming out of it. The smaller diameter tube near the high and low end screws is the fuel pickup. Can anyone tell what the slightly larger diameter tube on the opposite side is used for? Is it used for pressurizing the fuel tank? I've been to the Ryobi and the Walbro sites but can't find this particular carburetor. I'd like to get this engine running on a test stand before I stick it into an airplane. Joe L.
20 years ago