[Fot] TR6 race engine with 45DCOE triple Webers

[Greg Solow]

The F-16 emulsion tube are very lean throughout the rev range. try either f-2 or f-11 emulsion tubes.  begin with 145 main jets, and  165 air correction jets. the larger the air corrector, the leaner the mixture. I think that the pump jets are to large. Try 35 pump jets and pump inlet valves with a 70 bleed hole. The pump jets acts as part of the "high speed enrichment system" but you need the bleed or else the pump squirts in to much gas and can make the car bog or resitate coming out of corners. The idle jets are to large the the cylinder size. Try 45 f-8 or 40 f-6 idle jets. you may be able to go down to a 40 f-6 idle jet. This will help keep the engine from fouling plugs around the pits. 
       Part throttle mixuture reading do not mean much to me. Most of my experience has been WOT on the dyno where you want a "brake specific fuel consumption" figure of around .50 lbs of fuel per horsepower per hour.  Part throttle operation has to do withj "drivability" and not fouling plugs. You would generally want the engine to run as lean at part throttle as it can run without constant backfiring in the intake manifold. 
       Make sure you have spark plugs in the engine that are cold enough to work with the compression ratio of the engine.  An engine with 12.1:1 will need a Campion Racing plug with a heat range number like  C 61YC. On the dyno you might start with an even colder plug like  C59YC. just to make extra sure that you stay away from detonation. After getting things more dialed in, you can probably go to the warmer plug. 
                                                                   Good Luck, 
                                                                              Greg Solow      
  ----- Original Message ----- 
  From: Van Mulders Marcel via Fot 
  To: fot at autox.team.net 
  Sent: Thursday, December 29, 2016 1:45 PM
  Subject: [Fot] TR6 race engine with 45DCOE triple Webers


  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 new
  The 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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