Here's my understanding:
To richen the entire range, run a larger main jet / to lean out the
entire range run a smaller (lower number) main jet.
To richen the top end, run a smaller air correction jet / to lean out
the top end, run a larger air correction jet. The air correction is
the main top end mixture tuning device.
Changing the air correction jet has some effect on bottom end, so you
may end up going one step richer (larger) on the main jet and one or
two steps leaner (larger) on the air correction. Going from a 130 to
a 135 was a noticeable change both on the mains and on the airs, so
move slowly - if using the "track dyno", maybe make changes in the
10's and then refine down to the 5's. Going TOO lean is bad, so I'd
try to sneak up on it. I also found that the engine dyno gave me
much different settings that I came up with just trial and error on
the track using seat of the pants and EGT's.
Last time I went through that I was on a dyno with an air/fuel meter
so I could see when it went rich / lean. I found that running the
largest Choke tubes that I could fit (in my 42DCOE's) helped. I've
got a set of beat up 45's on the shelf that I hope to resurrect so I
can start that tuning process all over... :)
You don't say what your car is, but in my TR-4 I had to run richer
than "normal" (for a "normal engine") I suspect that's due to the
combustion chamber design (or lack thereof).
Tony Drews
At 08:17 AM 4/22/2011, Craig Leinicke wrote:
>Hello Paul,
>The looks and sounds awesome.
>Watching the video got me thinking about my TR7 weber carbs.
>Here is the current carb set up that I am running...
> Choke tubes -------- 30
> Aux. venturis ------- 4.5
> Main jets ------------ 125
> Emulsion tubes --- F9
> Air corr jets --------- 155
> Idle jets --------------- 55F8
> Pump jets ------------ 45
> Pump exh valve ---- 45
>
>My question to the group is... My car tends to run rich (full throttle land
>speed racing) and rich is better than lean.
>To lean the mixture which pieces should I change and which direction should
>I go... And how far?
>Thanks in advance for feedback... I'm racing mid-may at Maxton.
>
>Craig
>Flashback Racing
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