Yup.
Mixture is way lean, most likely, and the chokes aren't closing cold.
You probably also have bad accelerator pumps -- you should get a squirt
of fuel down the venturi on both carbs every time you open the
throttles.
The actual balancing isn't difficult, but it is fiddlesome, and you
MUST make sure the valves are adjusted correctly FIRST -- it will be
impossible to get both carbs working correctly if the air draw from the
engine isn't the same for both.
If they've been exensively fiddled about, here's what I would do:
Disconnect the linkage between the carbs. Set the idle speed screw so
that both carbs have EXACTLY the same opening -- use a set of drills to
measure the gap between the throttle plate and the bore. This is
fairly critical, as if you don't get started more or less right, the
engine won't run well enough to them set.
Close the mixture screws all the way in, then out EXACTLY the same
number of turns (if it sounds like I'm being picky, I am). I believe 2
turns, but dont' remember. If it won't start, try three. Make sure
you turn the screws the same amount each time.
Veryfiy that the chokes close cold, and open slightly at full throttle.
Veryify that you do not have serious vacuum leaks around the base (the
heat risers often stick, and warp the bottom of the carbs. This may or
may not be repairable). Plug all the vac lines, including the brake
booster.
Pump the linkage twice on each carb and the car should start. Allow it
to warm up until the chokes are fully open.
From here, what you want to do is block the idle air bleed on the
emulsion tube (the hole in the top plate of the carb) one at a time
while watching a tachometer -- adjust the idle mixture screws
individually to get exactly the same rpm drop when blocking one carb.
Set idle speed by turning the idle speed knob on both carbs the same
amount, then attach the linkage so that it does not change the
position of the throttle plates.
Final mixture adjustment should be done with a CO meter -- you want 1
to 1.5 ppm (up to three is permitted, but you will get really bad
milage at 3% CO -- more power, thoughy).
If you don't get good fuel spray from the accelerator pumps, you will
need to rebuild the carbs before you can get them set properly, of
course.
There is a fuel screen in the pump under the outer housing, I think,
and probably screens in the inlets to the carbs as well -- if they are
plugged, you may not be gettting adequate fuel during cranking. A bad
fuel pump will do the same thing, of course. You can test that by
disconnecting the fuel line to the carbs and directing the hose into a
proper (large enough) container and cranking the engine. You should
get a good slug of fuel for every engine rotation. If not, check for
tank or line blockage -- the gassers have the same screen in the tank
diesels do.
Hope this helps!
Peter
