I have a set of colortune devices. I have used them with no trouble on my
TR7. I got bunsen blue with minimal fiddling.
On my TR4a, I can not get blue EVER. I tried starting from a rich setting and
then gradually used the jet adjusting screw to lean it out. I could go lean
to the point of stalling and never get blue.
I then started with the rich setting and then used the lifting pin to create a
lean condition. I could get a faint blue color just as the engine stalled
from excessive lean-ness.
Does the collective wisdom of the list have any idea what could make the
colourtune devices to never show the blue?
For what it is worth, the lifting pins are not giving me a good indication
either. I ended up leaning out the carbs until the idle speed dropped, and
then enriched from there to restore the idle speed.
The engine seems to be running quite well! But, I am not sure if I am at the
ideal mixture position.
-Tony
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