Stu,
Never rebuilt the stock 2 barrel, but I can give some information on the
"idle" screws.
There are the original kind, which were pointy tapered ends fitting into
a cone, and acting as an idle fuel orifice. These are usually seated
lightly and backed out about 1 1/2 turns as a starting guess. After
warm-up, they are adjusted for good idle. There would probably also be a
throttle position screw to set the idle air flow, and nominal idle
speed. The idle jets looked for smooth idle, without a gasoline odor out
the tail pipe.
The newer designs were constructed to have the throttle plates closed at
idle. The adjustments were lager and actually adjusted an air-fuel
mixture flow rate by-pass of the closed throttle plate. The actual
mixture ratio was normally set by an internal idle jet orifice.
On a more elaborate carb, like a Weber, EVERYTHING was adjustable, by
either movable adjustments or replaceable orifices, jets, air bleed
orifices, and lots of other $100 pieces. {9->
Specifically, on the two barrel Ford Tiger carb, the system was an early
version of the air by-pass method. Fuel comes from the bottom of the
fuel bowl (through an internal passage), is mixed with air through a
small vent near the top of the main carb flow inside another downwards
internal passage. The fuel is metered by a calibrated restriction at the
top of this column. At the bottom is a pointy ended idle adjust screw.
This meters the fuel-air mixture into the main carb flow below the
throttle plates. It's usual starting position is 1 to 1 1/2 turns "out"
from a light seating in the "in" position.
As carbs go, this one is relatively simple. But, that is not to say it
is "easy" to dismantle, clean, reassemble, and adjust by the seat of
your pants. I strongly recommend the Sunbeam Tiger Workshop Manual,
available at Sunbeam Specialties for about $30, which covers re-building
the carb. For instance, you should remove these idle screws and check
that everything is in good shape, and the orifices can be leaned with
the appropriate solvents.
Good luck.
Steve
--
Steve Laifman < Find out what is most >
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