bing carbs jets on 3300 Jabs

[peter anson]

I have used a similar arrangement to Steve. I used the Jabiru intake and filter box but fabricated a metal cover. A NACA duct on the side of the cowl runs into a circular pipe which plugs into the rubber intake hose when the cowl is fitted. The metal cover on the airbox is fitted with a bell-mouth from Spruce. The rubber bend from the bell-mouth to the carb is just a bit of automotive radiator hose. I originally used it as a temporary measure but it's still there 3 years later and hasn't deteriorated noticeably. The forward facing pipe is normally fitted with a scat tube to the hot air intake.



My Bing uses the normal "economy tuning" jets and needle but with a drilled out choke jet. Power delivery is smooth, but going by spark plug colour it is running slightly rich. The air box is a really tight squeeze with the 3300 but would be easy to fit behind a 2200.

Peter
Sonex 894
190 hours

[ldmill]

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

Walter,
I changed from Aerocarb to Bing at 120 hours. Have 30 flawless hours on Bing now. I do not have cold air intake on mine and everything runs great. Started with factory economy jets but they we're too rich for my system. Ended up with a 276 needle jet and 255 main. My fuel line routing goes slightly down through the firewall and then slight elevation up through a filter then into the stock fuel pump. EGTs average 1310 at about 1780rpm where I cruise at 148mph indicated. I use a direct mount K&N air filter that Pete (USJabiru) said they use with no issue. I use a dual element electric carb heat setup I also got from Pete with no issues.

The setup is very simple and works well for me.

Lorin Miller
N81YX

[Corby202]

How big a NACA duct are you talking about Peter, VANS fresh air duct size??.How do you get to the air filter??
Thanks Phil

[peter anson]

My NACA duct is roughly 4" x 1", scaled up from the Sonex fresh air intake on the scientifically proven method of "yup, that looks about right". If it pushes in too much air, the Jabiru air box has a flapper valve to dump pressure. If the intake isn't big enough the engine could be gasping. I was originally intending to try some sort of breakable seal on the flapper valve to see if that was opening, or alternatively a fence at the back of the intake to push in more air, but I have never got around to either. The engine ran well so there wasn't much incentive to look for things that were wrong.
The air filter can be serviced by removing the rubber bend to the Bing and then removing the aluminium lid, just like the original Jabiru part. It's a real tight fit and you have to poke your tongue into the corner of your mouth just right, but it does come apart.
Peter
Sonex 894