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1. 12:08 AM - Re: Carb Jetting (Martin Hone)
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| Subject: | Re: Carb Jetting |
Hi Tex & Bob,
Your comments could not have come at a better time. I have just
checked the main jet on a Bing fitted to a J230, and despite being
marked as #255, it measured at #250. I have since reamed it to #260
Cheers
Martin
On Wed, Jan 26, 2011 at 10:58 AM, Tex Mantell <wb2ssj@frontiernet.net> wrote:
> Bob, I had almost the same problem when trying to rejet my carb. The jets
> from bing and others are not the actual sizes marked on the jets. Some are
> larger then marked and some are smaller then marked. Take a good set of
> drills and check each one. After I found this out I would get the result
> expected when changing a jet. Tex
>
> ----- Original Message -----
>
> From: BobbyPaulk@comcast.net
> To: jabiruengine-list@matronics.com
> Sent: Tuesday, January 25, 2011 11:35 AM
> Subject: JabiruEngine-List: Carb Jetting
> Mike
> My first carb was running EXTREMELY rich on the standard jetting and nothing
> I did would lean it out. The soot would build up in the exhaust pipe and the
> plugs were covered as well. I was cleaning the plugs every 5 or 6 hrs.
> Jetting, changing float level, and the inlet needle valve did not make any
> difference. Make sure you are using the newer black floats. I know for a
> fact that the original white floats could not shut off the fuel flow at 1.7
> psi on that carb.
> My second carb with the black floats was running extremely lean with the
> standard jetting. ( Go figure ) When I went into it I discovered it had a
> 250 main jet in lieu of the standard 255. I have since re jetted to the 255
> main and then up to a 260. Also I have upped the needle jet in stages up to
> a bored out 290 to 295. I have finally got it running some where in the ball
> park with no adverse change in fuel consumption.
> I do not understand how the same size and make carb can give such different
> performance with the same parts except for the floats.
>
> At cruise settings my front two cylinders are running 150 deg. hotter EGT (
> 1340 ) than the rear ( 1190 ~ 1200 ) with the middle two in between. CHT on
> the front cylinders are relatively cold 250 ~ 260 and rear cylinders right
> at 300. I had to modify my Ram Air ducts, get rid of the butterfly baffles
> on top, and make Lycoming type baffles on the bottom of the cylinders to get
> to this point.
>
> Bobby
> 113 hrs.
> 601 XL
>
>
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>
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