Online Community of Zenith Builders and Flyers
Hello...i am running a 3300A with a bing carb. lately i have been having issues. If i pull the throttle cable back till it stops it stalls the engine...if i adjust the cable to full throttle it starts missing during climb out like it has too much fuel and i have begun having issues with carb ice. at least it acts like carb ice when i pull on the carb heat it runs rough and then straightens out....my worst issue is the engine stall...anyone have similar issues and fixes?
I actually like the Bing, once I understood the different systems and how they are supposed to work. The sensing port was very rough inside and once cleaned and smoothed out made an improvement, as it gave more air energy to the atomizer to shear fuel. This is why it is very critical to make sure there is nothing remotely in front of this port entry, located at the 6 o'clock position of the carb air entry. Even an air elbow that is too close to the entry can influence this port..
i will look for that...I plan on getting a rebuild kit and installing it
Inflight shutdowns should NOT be the norm.
Once you accept it as the norm, you are the test pilot of a poor design.
Now, be 100% sure your throttle cable support bracket is 100% attached to the engine, and not to the firewall. If it is attached to the firewall, the thing will shut down at every landing
thanks jan...will check it
I realize that I'm late to this discussion, but I didn't start phase 1 until mid July. I've built a 750 Cruzer with a new 4th generation Jabiru 3300 with a Bing carb and the dual throttle set up using a Whirlwind ground adjustable prop set at 15 degrees. I have not had problems with the engine stalling when I pull the throttle back. My problem is with the response curve when I push the throttle in. As I push the throttle forward, the rpm's increase steadily to about 2700-2800, and the fuel flow increases steadily (The engine does seem to run a little rough at that point, and smooths if I back off a bit on the throttle). This increase in rpm and fuel flow occurs smoothly up to the point the throttle is about 1/2 to 2/3 advanced. Beyond that point, the rpm's begin to drop and the fuel flow increases. Suggestions? Is there a top end stop that needs adjusting?
I am also wondering if there is a better throttle control for dual throttles mounted laterally on the panel than the solid rods sticking through the panel that come with the Zenith/Jabiru FWF kit. I would really like to have friction locks and vernier controls on the throttles. I saw the lever type that aero conversion offers. Is anyone aware of other alternatives?
McFarlane makes a "Vernier Assist" throttle - it's a push-pull throttle with a friction lock - you can leave it in any position and then twist the vernier knob to fine-tune the setting. I have the "Vernier Assist" mixture control and am about to install the throttle, too, because I like it so much!
I just installed my Vernier-Assist throttle the other day and flew it. I really like the ergonomics - when you lay your hand on throttle knob, the fingers naturally fall on the knurled friction adjustment knob. You can push-pull the throttle to get an approximate setting, then fine-tune the rpm's with the vernier assist by twisting the knob. Supposedly this is a "jam-proof" design as opposed to other vernier throttles - works great!
John: Thanks for the suggestion. I ordered McFarlane's vernier assist custom cable for the pilot's side and installed it--works great--much better control than the old rigid rod. I also ordered McFarlane's friction lock, without the "guts" , for the co-pilot side.
I replaced the main jet that came with the carb (255), first with a 250 and then with a 245. That has helped overall performance, but it still has a tendency to peak on RPM, and then fall off, just before wide open throttle. Don Burkholder suggested checking the scat tubing into the carb, and that will be my next move. Thanks, Tom
Hi Thomas. Did you try backing off the 15 degree prop setting slightly? Just small fractional increments to reduce the load? Other than this, what size main jet do you have? Do you experience uneven exhaust temps at full throttle? The bottom of the Bing air horn has a large port that must not have anything near it as this provides a pressure differential across the atomizer and fuel needle port.
3300's extra length and tighter firewall clearance shortens the distance the air has to become laminar before reaching the air horn. My shorter 2200 had an elbow that allowed a 4 to 5 inch straight leg to the entry of the carburetor. Example? Scat hose has been known to "bunch up" near the air horn causing issues.. My previous posts involved my Bing modifications and may be of interest.
Hope this helps..
Merry Ho Ho
Don: Thanks for the suggestions. I have adjusted the prop slightly, and that helped. My engine came with a 255 main jet, and I moved first to a 250 and then to a 245. That has also helped. Next time I have the cowl off, I'll pay careful attention to the scat hose leading to the carb and will make it as straight as possible. I just searched for your prior posts on the Bing, but did not find them. Tom