Message text written by Darrell Walker
>I got a good deal on the Gunson Gastester, which I always wanted because I
really don't trust myself with the other common methods of setting the
mixture. The only problem is that the manual says to use the
manufacturer's
specification for the CO level, which I can't find that Triumph documented
anywhere (likely because cheap CO meters were not widely available in the
50's and 60's). The Gunson manual does say a typical level is between 0.5%
and 3.5%, but does anyone have an idea on what I should be shooting for?
Right now I'm measuring around 2.5%, and from the tailpipe (black and
sooty)
I'd say I'm running rich, but the lift the piston test says I'm running
lean
(which is why I wanted the testing in the first place!).
<
Darrel, if you read the manual that came with the tester it will tell you
that the meter actually reads CO2 and is calibrated to indicate the
corresponding CO. The two are inversely corrolated and a maximum CO2
content equals a min CO content. Unfortunately, CO2 peaks at
Stoichiometric conditions. Moving either side of Stoichiometric will
result in a lower CO2 content and a higher CO reading. The problem is you
may be on the wrong side of Stoichiometry will give you the reading you
want but under conditions that are all wrong.
I suggest you set the mixture as close to what you want using the
lift-the-piston method and then resort to the Gunson. (Please note that
the lift-the-piston relies on lifting the piston the exact prescribed
distance and your carbs should have an integral lifting pin for just this
purpose. Use it.)
BTW, I don't know what reading you should be striving for.
Good luck
Dave
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