Here is my engine with the venturi adapter my friend Dan Banjock made for me. The idea came from others on here and also from a Stels engine I own. The Stels engines I've mainly seen have the spraybar and needle assembly going right through the case. The engines will not run on suction due to the large bathtub opening in the case and generally run on bladder. The engine I own has the same bathtub opening in the case, but it has nylon like inserts which are threaded and accepts a Tee Dee venturi setup. On the AP I'm using the ACE unit which is the black plastic part and a fine needle from a Cox production backplate. The spraybarsfrom the production backplate can be pressed out and into the ACE unit. Essentially, I have a cheaper version of the Kirn Kraft unit. I just cut the needle down considerably and solder a washer onto it. This keeps it out of the way when the engine decides to go hunting for worms. The adapter though is quite simple as it uses a 1/4-32 thread for the Tee Dee stack and 2 set screws from wheel collars to hold it in. The AP case has two very fine screws to hold the stock r/c carb in and the case has been tapped to accept the two 4-40 set screws. The plane in the picture is built from Phil Cartier Lil Hacker wings. It finished at 4oz's. The AP is turning a APC 4.6 x 3 on 35% nitro in the 27K+ range is doing quite well. I'm impressed with this little engine. I'm using the stock Cox venturi undrilled and I'm quite sure I could use the engine for stunt as well. I'm using the Merlin plug, but I had to add a lot of head shims due to it blowing plugs. I have .021 of shims in the engine now. Ken