Steve---Your float level is OK at 17mm. One spark plug a little "whiter"
than the others shows up in several TR's that have come my way. (#4 is
the light one in my engine. Always has been, and I've never been able to
uncover the reason)
Still, you can do some checks to see if any unmetered air is coming in
close by the cylinder with the lighter plug. Besides the usual vacuum
lines, also check around the carb gaskets or intake manifold gasket.
Some use carb cleaner for such a check. I find it safer to use the gas
fumes from a propane torch. Connect a hose to the torch tip so you can
bend it up under the manifold. If the engine speeds up...viola!
Your plug coloring seems about right also. You can try raising the
needles a little, to see if it helps the off-idle stutter. Know that
this will darken the plugs even more when the engine idles.
Dick
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