Online Community of Zenith Builders and Flyers
I have a Zenith 750 Cruzer with a 4th Gen Jabiru 3300 with a Bing carb. Yesterday I discovered significant "kinks" in the scat tubing I used to connect the carb air horn to the filter/carb heat box. I understand that it is important to have smooth non-turbulent airflow through this tube, preferably with a 5-6" straight run before the carb. That's hard to achieve with the proximity of the nose gear strut. Has anyone found a better way to do this than with scat tubing?
Hi. Yes, scat is no good..Exactly, how much distance do you have from the air horn of the Bing to the strut AND is the center line of the Bing to one side or the other of the strut. You may have some options... Pictures would be nice, maybe a straight down shot and a side shot as well after removing your cowl and any air ducting etc..
I now use an AeroInjector carb on my 750 STOL's 3300, but when I had the Bing, I rummaged through an auto parts rubber hose bin until I found a near-90 degree rubber hose bend. It is molded so there are no kinks and the inside was absolutely smooth. Pete at Jabiru USA also gave me an airflow straightener (has vanes inside in an X cross-section) to straighten the airflow between the bend and the carb - worked great!
Here's a pic of that same rubber bend, but connected to my AeroInjector rather than the Bing. The Bing mounted right on the back of the plenum, leaving room for the "straightener" between the rubber bend and the carb.
There's nothing wrong with the Bing, but I prefer to have a manual mixture control and like to experiment, so that's why I switched to the AeroInjector. Since the AeroInjector doesn't need carb heat, I eventually deleted the air box and put a K&N air cleaner directly on the carb and also fabricated an aluminum intake runner to the plenum: