What a curious problem. Were your manifolds manufactured for use with Weber
DCOEs or were they adapted from some other application?
Duncan Charlton
Elgin, Texas USA
> On Jan 1, 2017, at 6:03 AM, Marcel Van Mulders via Fot <fot at
> autox.team.net> wrote:
>
> Plugging the balance pipes (1/2" diameter and between every inlet tract of
> the manifold) did solve the problem : at WOT and 5000 rpm the AFR went down
> from some 16 with open balance tubes to 10.2 with plugged tubes, both with
> 180 main jets wich have now prooved to be too big. The cold engine does start
> easily know. With the open balance pipes, I had to crank the engine a lot :
> the engine was running a second and stopped. (accelerator pump). Probably
> every single cylinder did suck mixture from the other inlet tracts too, via
> the balance pipes, thus weakening the signal at its own Weber tract?
> Are we in 2017 now?
> Marcel
>
> Van: Greg Solow [mailto:Gregmogdoc at surfnetusa.com]
> Verzonden: zaterdag 31 december 2016 01:48
> Aan: Van Mulders Marcel; fot at autox.team.net
> Onderwerp: Re: [Fot] TR6 race engine with 45DCOE triple Webers
>
> 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 -----
>> 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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>>
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