bing carbs jets on 3300 Jabs

[WALTWESTER]

Any one using a Bing Carb on their 3300? If so, what combination of main and needle jets have worked out for you?
Thanks Waltwester@earthlink.net

[sonex892]

Any one using a Bing Carb on their 3300? If so, what combination of main and needle jets have worked out for you?
Thanks Waltwester@earthlink.net

I have only used the bing, still using needles it came with from the factory. All I know is it has the economy tuning setup and could not tell what jets they are.

It has worked flawlessly now for 150hrs. I have carb heat and a naca duct inlet for intake air.

I would suggest making sure the intake air is sorted before messing around and changing jets. By that I mean not drawing intake air from inside the cowl. You will also need a smooth airflow into the carb, No scat tube! Due to the lack of space Sonex owners are tempted to set it up like an aerocarb. Jabiru Aus will tell you not to it. A friend of mine tried it on his 3300 powered Sonex and it ran like a dog at higher power settings, It sounded terrible from the ground. After about 5 hrs of testing he changed to a fresh intake air it made a world of difference

[DCASonex]

Have that setup. Due in large part to bad hydraulic lifters (long story told preciously) had reason to experiment, not all with good results, but now have what seems to be a very good functioning combination A 2.82 mm needle jet with an economy needle that has been slimmed down a bit at its swelled section. 2.80 needle jet, or slightly less slimming of the needle might be best if flying in warm weather, but I am purposely running just a tad rich so as to be able to lean with HACman for best cruise in wide range of altitudes and temperatures.

Have a drawing showing my needle profile, e-mail me if interested. If doing any needle and/or jet modifications, strongly suggest you do it with a spare set. Started with 2.80 mm (0.1102" - #35 drill bit) needle jet and reamed out to 2.82 mm with # 34 drill bit. 2.85 was too large, and ran too rich at low RPMS. Mixture needle was no longer effective with this jet, but works with the 2.80 and 2.82 mm jets.

As has been said by many before, your mileage may differ. Precise tuning seems to vary with air frame, prop pitch, prop diameter, fuel, intake system (I have filter directly on the carb, no outside air intake) , and phases of the moon.

Have had good success with current setup on both new CAMit engine and in brief trial with carburetor and entire intake system from new CAMit engine transferred to reworked old Jabiru engine.

David A.

[pgerhardt]

I have a 3300 with the Bing. The first 90 hrs or so were with the stock economy jets that came with the engine. Last year I leaned it up some by changing both the main and needle jets. I did this twice but can't remember what size is in now. It is still a bit rich and want to try a Hacman this year. I did put in all six thermocouples for both EGT and CHT. My main issue it seems it that the EGT are uneven front to back.

1&2 1320 or so
3&4 1100 or so
5&6 950 or so

nice and even right and left and CHT are 'OK' with #3 running the warmest.

Filter is on carb air intake in the cowl.

225 hrs and it runs well but would love to have it more even and a bit leaner in cruise.

Paul
N148YX

[WALTWESTER]

Thanks for the replies on the Bing jets/needles. Gives me something to start from WaltW

[DCASonex]

I have a 3300 with the Bing. The first 90 hrs or so were with the stock economy jets that came with the engine. Last year I leaned it up some by changing both the main and needle jets. I did this twice but can't remember what size is in now. It is still a bit rich and want to try a Hacman this year. I did put in all six thermocouples for both EGT and CHT. My main issue it seems it that the EGT are uneven front to back.

1&2 1320 or so
3&4 1100 or so
5&6 950 or so

nice and even right and left and CHT are 'OK' with #3 running the warmest.

Filter is on carb air intake in the cowl.

225 hrs and it runs well but would love to have it more even and a bit leaner in cruise.

Paul
N148YX

Paul,

Try removing the center airfoil that is inside the intake manifold and replace it with a simple 1/2' dia. round bar. That brought my temps quite a bit closer together. Be sure to re-seal the pipes coming out from that to the cylinders. I think that was # 2 Permatex. (RTV does not like exposure to fuel).

This has been much discussed over the years on the Yahoo Jabiru forum.

David A.

[pgerhardt]

David

I have read all the discussions and but have not yet tried removing the airfoil. Will do that next month.

I also bought an X vane but not sure that will do anything. Will try one at a time...

Paul

[Corby202]

It has worked flawlessly now for 150hrs. I have carb heat and a naca duct inlet for intake air.

You will also need a smooth airflow into the carb, No scat tube!

Hi Steve
Could you please elaborate on this. Naca duct, Jabiru supplied?? How do you connect the Naca duct to the heat box, Jabiru supplied?? and then to the Carbi if you are not using scat tube.
Thanks
Phil

[sonex892]

Hi Steve
Could you please elaborate on this. Naca duct, Jabiru supplied?? How do you connect the Naca duct to the heat box, Jabiru supplied?? and then to the Carbi if you are not using scat tube.
Thanks
Phil

Hi phil.
I should have said try not to use scat tube as an inlet to the carb especially if there are any bends. If you have the room, scat tube would be fine to connect the naca duct to the airbox.

I think Jabiru would still supply Naca ducts and airboxes. I actually made my own naca duct/airbox setup purely because on the 3300 there isnt much room to do anything. This is my second Jabiru powered homebuilt. The only problems I had with the first were all related to air induction problems.

Here is a construction photo which hopefully shows how it works. The cowling piece plugs into the airbox as the cowling is fitted

More photos of the airbox connection to carb etc are in this old thread
viewtopic.php?f=8&t=1806&p=13395&hilit=bing#p13395
Cheers Steve

[DCASonex]

David

I have read all the discussions and but have not yet tried removing the airfoil. Will do that next month.

I also bought an X vane but not sure that will do anything. Will try one at a time...

Paul

I have the intake air filter directly mounted on the carb, and the X vane had no effect with that. Many reports that it does seem to help if you have an elbow directly into the carb.

David A.