Tom Boggiano writes:
>
> I have a question for those who have a color tune, having lost my
> instructions and not having a memory like I use to what does a orange
> looking color mean ( too righ too week ). I thought the desired color
> tune color was blue am I correct.
>
I just went through this on my 68 MGB, which has 67 smog equipment,
but passed 68 smog specs with no problem.
You want to find the border between yellow and blue, with yellow
being too rich (black body radiation from the soot) and blue being
leaner (CH radical emissions). If I leave it at this point, it is slightly
rich, giving good power. Two flats leaner on each carb cuts my CO and HC
emissions in half (but probably raises the NOx) but still gives smooth
running. The colortune will tell you when you are too lean by showing
misfires, but there is a range of 4 flats around the optimum setting
where I can't see much change in the colortune reading. I find the colortune
much easier to use after dark.
-Jean H
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