[Fot] TR6 race engine with 45DCOE triple Webers

[Rick Parent]

The chokes are too big, there is not a good enough signal to draw the fuel out of the main well. 

    On Friday, December 30, 2016 10:30 AM, Duncan Charlton via Fot <fot at autox.team.net> wrote:
 

 How far downstream of the exhaust valves is the Lambda sensor installed, and how far from the exhaust system outlet is it?  You mentioned having checked for air leaks, but didn’t say whether you checked both intake and exhaust.  Is the dyno operator also using a lambda sensor?
This comment is not specific to the TR6 but since it’s leaning out at the high end I would have initially guessed that your air correction jets are too large, but one typically expects the AC jet to have a number about 50 higher than the main jet, whereas your AC jets are nearly the same number as your original main jets and a lot smaller than your second main jets choice.
According to the Weber choke selection chart the 35mm chokes correspond to a maximum output of 6000 rpm so 36mm seems fine unless the engine’s desired max output is a lot higher than that.
Duncan CharltonElgin, Texas USA



On Dec 29, 2016, at 3:45 PM, Van Mulders Marcel via Fot <fot at autox.team.net> wrote:

The engine for a friend's TR6 racecar is finished at last and it has run a couple of times now.I have a problem with the mixture : the air correction jets are 155, I started with 140 main jets but the mixture was much too lean : AFR was 14 at idle and 17 at 5000 rpm. Even with 180  main jets, the AFR  is still 15 at 4000 - 5000 rpm. The engine is 2720 cc and 12.6 volumetric CR.The Webers are secondhand, 45DCOE type 152 and they look as newThe venturis are 36mm, emulsion tubes are F16, idle jets 55F8 and aux. venturis are 4.5. Pump jets are 40 without a bleed hole. The plugs have a correct colour, no sooting, no signs of overheating. The engine is on a dyno but I didn't risk so far to really load the engine, so the plugs doesn't tell much. The lambda sensor is a wide Bosch sensor, about new and with an Innovate controller. I suppose 180 main jets are already too big. I can't find any air leaks and the spark plugs have all the same colour. Is it possible that 36mm chokes are too big? Any idea's why the mixture can be too lean, even with 180 main jets? Should I suspect the lambda sensor/Innovate controller? What venturis should I start with? Another question : I have no experience about the range of total ignition advance a full race TR6 engine does need.Marcel _______________________________________________
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