List, I also have the same situation as described by Mike which
I have included below although I have never seen the reference
to the bearing height he describes. In desperation, I lowered
my needles about 1/16" BELOW the bottom of the piston and I
can finally adjust the mixture nuts to something other than
fully up tight. I finally need to use the choke to start the
engine which I have never had to do above 50 degrees. I have
long suspected that the top bearing washer is too thick but
leaving it out lets the large sealing nut bottom out before
the jet assembly is tight. I also would like to know the
thickness of that washer and how far below the bridge the
jet sits when the mixture nuts are up tight. Any help please.
Bob
TR3A TS39869L
Subject: TR3A SU Carb - Mixture too rich
I purchased a '58 TR3A that has been "restored" and have been having trouble
getting the fuel mixture correct. It runs rich as identified by the carbon
sooted plugs and the use of a Gunson Colortune. After checking fuel filter,
fuel pressure, floats, ignition/timing, etc., I decided to dig into the SU's.
The mixture adjusting nuts were set completely up (tightened) as far as they
would go, so there's no way to make it run any more lean by
changing these. I've also found some things that don't match the Haynes SU carb
book or other notes that I have found online.
The book states that when the adjusting nut is screwed up as far as it will go,
that the jet will be protruding into the bore. This is not the case on mine.
With the adjusting nut all the way up, the upper jet bearing is just under
(about 1/16") the level of the bridge and the jet is about 1/16" below the top
of the upper bearing.
Also, the needles are marked "369". I can't find any reference to this specific
needle marking.Does the fitting of the upper jet bearing and jet sound correct?
Could the needles be wrong?
The carb is tagged AUC786. The bore is marked AUC6040AC. The jet is .100".
Thanks for your help.
Mike
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