Steve---When an engine runs better with the Choke pulled out, it could
be any or all of at least three things:
First check to see if there's any obvious vacuum leak. You should hear
the hiss of one that's capable of upsetting the engine, as yours does.
(A vacuum gauge helps here, as would judicious use of a propane gas)
Or...The carb needles need to be raised. Use the "special adjusting
wrench" or a long handled 1/8" Allen wrench to get to the bottom of the
tube where you put the damper oil. Note: There should have been oil in
them. Counting the quarter-turns screw the adjustment clockwise till
it resists turning. (Usually about a full turn or two) This will make
the carbs run full rich. If this still doesn't eliminate the need for
using the Choke, return the adjustment to something less than "full
rich" and next check this:
With the air cleaner box off, look inside the carbs as you operate the
throttle lnkage "by hand". With the engine running of course, both of
the air valves should raise the same amount as you speed up the engine.
If they don't, check that the linkage pulls evenly on each of the
throttle plates. If they do, next check that both diaphragms under the
top of the carbs are hole-free. (Tho not typically the reason for
misfires, they're easy to take in and out to visually check.)
It's difficult to cover all that could be wrong in this forum, but...
If everything in the carb area now looks good and you still have the
need to use Choke, even with a warmed up engine, we will next look at
the possibility that your spark is out of phase with the cap towers.
Thus the need for the large advance that you wrote of. We'll explore
this after the above checks, if you wish.
Dick
'73
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