I suspect all you experts on this list are going to roll your eyes at this
enquiry, but as a newcomer to this business of being my own mechanic
(although I did own and drive a TR 2 way back in 1959/60.Wives and family
have filled the intervening space), I am currently attempting to what
laughably seems to be called "tune" the SUs on my recently acquired 1957 TR
3A (of uncertain historyand a bit worn round the edges, although she goes
and stops reasonably well, and seems to have mostly original parts).
Following the instructions in a variety of manuals including Hynes and
"Practical Hiints for the Maintenance of the TR 3", I balanced the air flow
as best I could using a length of tubing, then with the engine idling at
about 700rpm, I lifted the piston of one of the carbs the requisite 1/16
inch, at which point the revs increased slowly, supposedly indicating the
mixture is too rich : I turned the adjustment nut one flat up (leaner?) and
found to my suprise that the nut was virtually at the end (fully closed) of
it's travel.
Does this mean that the jet/needle is so worn that there is fuel flowing
even when the throttle is closed? Both carbs seem to be the same. This
attempt at tuning was prompted in large part by finding the plugs with a
black deposit after a longish outing. The engine has been "reconditioned"
and uses virually no oil, and the exhaust is clear. I had diagnosed too
rich a mixture.
Dave.
TR 3A 1957
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