My results are similar. A couple of weeks ago I decided to adjust my HS4's on
the 77B 110 mile/day commuting machine. Gas mileage has consistently been
around 21 mpg and I hoped to improve upon that. A couple of weeks before this I
had tuned the carbs with the hose/piston raise technique and the car was running
quite well. The ColorTune had me adjust both carbs by turning the nuts up about
three flats. This put me on the edge of yellow/blue.
A couple of weeks, and over a thousand miles later, the gas mileage is still
around 21 mpg, the engine is slower to start on cold mornings and has a rougher
idle. This week I'll be resetting the carbs via the piston lift technique.
Bud Krueger
52TD
77MGB
David Councill wrote:
> I bought the Colortune kit about three or four years ago. It came without
> instructions so I posted my dilemma on this list. Another lister made a
> copy of the instructions and sent them to me.
>
> However, I was not impressed. It worked okay, not like your problem. I only
> had to make some minor adjustments. But it didn't really improve upon my
> standard way of adjusting my SU carbs - both BGTs run great just by setting
> the fuel setting to the default of 12 flats (taking the nut from its
> position of being rotated to the top and then loosening it by 12 flats
> which I believe equates to 2 full rotations). That is my summer setting. I
> turn it down two more flats for my winter setting which is because winter
> temps are typically 60-80 degrees cooler (F) here in Montana.
>
> I was actually concerned that the Colortune jit would throw my carbs out of
> synch because I was setting each carb to a different fuel setting. And in
> the end, I just reset my carbs back to the way I always have them. Of
> course, the default settings assume the carbs are in good shape -
> particularly in regards to wear around the throttle shafts.
>
> David
> 67 BGT
> 71 BGT
>
> >
> >In setting the mixture by color, it took a LOT of leaning out from my
> >initial carb setting to get the flame color to go from yellow to
> >blue. With both carbs adjusted for bunson blue flame, idle was
> >rough, and out on the road the engine stumbled badly (too lean?)
> >Also, in looking at ignition, there seemed to be a lot of
> >uneveness--you could watch the flame color change / drift from blue
> >to yellow-blue.
> >
> >
> >My first thought is that I don't know anything about the cam, and
> >that maybe the problem is that it isn't stock, and has too much
> >overlap (exhaust gas contaminating the mixture, requiring richer
> >mixture?) But I am baffled. Anyone have experience with the
> >ColorTune? Is it a mistake to use it on a dual carb LBC? Is the
> >"lean drop" method superior if you don't have to pass smog tests? I
> >feel lucky that I don't have to smog it--as it sits it probably
> >wouldn't pass...
> >
> >
> >
> >
> >
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