Zenith Aircraft Builders and Flyers
Online Community of Zenith Builders and Flyers
Jabiru 3300 with bing carb. - info on jetting
I have a Jabiru 3300 made in 2003 (serial #33A489). Recently the engine began to run very rough and some plugs on the pilot side were wet. (I don't have any EGT's to know how rich it was running). Engine has solid lifters and calls for 2.80 main jet and 2.80 needle jet per Jab overhaul manual (2013). That is what it has now.
Apparently, in 12/2005 there was a change in jetting to "economy" with a 2.85 needle jet, 2.55 main jet and a special needle.
What can anyone tell me about this and if I should switch to the new jetting.
I will tilt the carb bowl to the lean side as Jabiru suggests but wonder why I am now (at 125 hours) having this problem.
It all seemed to start when I engaged my carb heat on a warm day at run-up. There is no debrie in the float bowl or air filter; carb heat flapper works as it should.
COMMENTS PLEASE
Replies to This Discussion
-
Permalink Reply by Darryl Legg on
-
Hi Carl
I have a later serial number, #1928, the engine ran too rich from the start. I put in a 2.45 main jet and no problems since. I do have EGT monitoring though. My home airfield is at 1500ft so I am really tuned from that elevation up. I also mainly use mogas ULP98 95% of the time.
I would recommend fitting some sort of EGT monitoring to your Jab, on all 6 cyls as 1 cyl could be lean and others too rich.
Also check that both sets of mags and plugs are firing, if no problems for 125hrs. This is also easily checked when monitoring all EGT's.
Good Luck....
-
Permalink Reply by John Austin on
-
Ditto Darryl's advice!!!
Since the 3300 is a 6 cylinder engine with a single carb, you must have 6-cylinder EGT and CHT probes to have any hope of accurately tuning, jetting, and operating the engine within normal design parameters. Yes, you can "read the plugs," but once you have 6-cylinder monitoring, you'll find that EGT's can vary cylinder-to-cylinder considerably depending on if you're climbing or cruising.
The Grand Rapids EIS 6000 is a good basic unit, although it's alpha-numeric data. (It has a tiny dot-matrix graphical screen which is not very useable.) Of course, your pocketbook's the limit as you go into the graphical display engine monitors, but a MGL XTreme EMS is a good engine monitor and doesn't take up too much panel space if you don't want a large EFIS.
Money spent on engine monitoring will pay off since it will allow you to accurately jet your engine for best EGT's and fuel economy, and prolong the life of your engine. Pete from Jabiru USA (now Jabiru North America) has an excellent article called Tuning the Bing Carburetor..
John
N750A
New from Zenith:
Classified listing for buying or selling your Zenith building or flying related stuff...
Custom Instrument Panels
for your Zenith:
Custom instrument panels are now available directly from Zenith Aircraft Company exclusively for Zenith builders and owners. Pre-cut panel, Dynon and Garmin avionics, and more.
Zenith Homecoming Tee:
Flying On Your Own Wings:
A Complete Guide to Understanding Light Airplane Design, by Chris Heintz
Builder & Pilot Supplies:
Pro Builder Assistance:
Transition training:
Aircraft Spruce & Specialty for all your building and pilot supplies!
How to videos from HomebuiltHELP.com
Developed specifically for Zenith builders (by a builder) these videos on DVD are a great help in building your own kit plane by providing practical hands-on construction information. Visit HomebuiltHelp.com for the latest DVD titles.
© 2024 Created by Zenith.Aero.
Powered by
